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I 


THE  MANUFACTURE 
OF  PAPER 


BY 


R.   W.  SINDALL,  F.C.S. 

CONSULTING  CHEMIST  TO  THE  WOOD  PULP  AND  PAPER  TRADES;  LECTURER 
ON  PAPER-MAKING  FOR  THE    HERTFORDSHIRE  COUNTY  COUNCIL,  THE 
BUCKS    COUNTY    COUNCIL,    THE    PRINTING    AND  STATIONERY 
TRADKS    AT    EXETER    HALL,    I9O3-4,    THE  INSTITUTE 
OK  PRINTERS  ;  TECHNICAL    ADVISER    TO  THE 
GOVERNMENT  OF  INDIA,  I905 

AUTHOR    OF    "paper    TECHNOLOGY,"    "THE     SAMPLING     OF     WOOD  PULP" 
JOINT  AUTHOR  OF  "THE  C.B.S.  UNITS,  OR    STANDARDS  OF  PAPER 
TESTING,"    "THE,  APPLICATIONS    OF    WOOD  PULP,"  ETC. 


WITH  ILLUSTRATIONS,  AND  A  BIBLIOGRAPHY  OF  WORKS 
RELATING  TO   CELLULOSE   AND  PAPER-MAKING 


NEW  YORK 
D.  VAN  NOSTRAND  COMPANY 

23  MURRAY  AND  27  WARREN  STREETS 
1912 


1 


;  -  r 


PREFACE 


Paper-making,  in  common  with  many  other  industries,  is 
one  in  which  both  engineering  and  chemistry  play  important 
parts.  Unfortunately  the  functions  of  the  engineer  and 
chemist  are  generally  regarded  as  independent  of  one 
another,  so  that  the  chemist  is  only  called  in  by  the  engineer 
when  efforts  along  the  lines  of  mechanical  improvement 
have  failed,  and  vice  versa.  It  is  impossible,  however,  to 
draw  a  hard  and  fast  line,  and  the  best  results  in  the  art  of 
paper-making  are  only  possible  when  the  manufacturer 
appreciates  the  fact  that  the  skill  of  both  is  essential  to 
progress  and  commercial  success. 

In  the  present  elementary  text-book  it  is  only  proposed 
to  give  an  outline  of  the  various  stages  of  manufacture  and 
to  indicate  some  of  the  improvements  made  during  recent 
years. 

The  author  begs  to  acknowledge  his  indebtedness  to 
manufacturers  and  others  who  have  given  permission  for  the 
use  of  illustrations. 


CONTENTS 


PAGE 

PREFACE    V 

LIST  OF  ILLUSTllATJONS  ix 

CHAPTER 

I.  HISTORICAL  NOTICE  1 

II.  CELLULOSE  AND  PAPER-MAKING  FIBRES    ...  20 

III.  THE  MANUFACTURE  OF  PAPER  FROM  RAGS        .         .  47 

IV.  ESPARTO  AND  STRAW  72 

V.  WOOD  PULP,  AND  WOOD  PULP  PAPERS      .         .  .95 

VL  BROWN  PAPERS  AND  BOARDS  126 

VII.  SPECIAL  KINDS  OF  PAPER  137 

Vin.  CHEMICALS  USED  IN  PAPER-MAKING  .         .  .153 

IX.  THE  PROCESS  OF  "  BEATING"  175 

X.  THE  DYEING  AND  COLOURING  OF  PAPER  PULP  .  199 

XI.  PAPER  MILL  MACHINERY  .         .         .         .  .214 

XII.  THE  DETERIORATION  OF  PAPER        ....  229 

XIII.  BIBLIOGRAPHY  253 


INDEX  273 


LIST  OF  ILLUSTRATIONS 


FIG,  PAGE 

1.  SHEET    OF    PAPYRUS,    SHOWING    THE    LAYERS    CROSSING  ONE 

ANOTHER      .          .                  .......  3 

2.  AN  EARLY  PAPER  MILL  (fROM  "  KULTURHISTORISCHEN  BILDER- 

BUCH,"  A.D.  1564)   10 

3.  THE  PAPER  MILL  OF   ULMAN  STROMER,   A.D.   1390  (SUPPOSED 

TO  BE  THE  OLDEST  KNOWN  DRAWING  OF  A  PAPER  MILL)  .  12 

4.  THE  FIRST  PAPER  MACHINE,  A.D.  1802.     PLAN  AND  ELEVATION  17 

5.  THE  IMPROVED  PAPER  MACHINE  OF  A.D.   1810         ...  18 

6.  A  RAG  SORTING  HOUSE   47 

7.  A  RAG  DUSTER   49 

8.  A  RAG  CUTTER   50 

9.  INTERIOR  OF  PAPER  MILL  FOR  HAND-MADE  PAPER  (r.  BATCHELOR 

&  sons)   51 

10.  view  of  a  rag  boiler,  showing  connections  ...  52 

11.  a  breaking  and  washing  engine       .....  54 

12.  oettel  and  haas'  apparatus  for  the  manufacture  of 

electrolytic  bleach  liquor   58 

13.  the  "  hollander  "  beating  engine  .....  59 

14.  the  hand  mould,  showing  frame  and  deckle  ...  61 

15.  apparatus  for  sizing  paper  in  continuous  rolls  .       .  63 

16.  a  supercalender   65 

17.  the  first  watermark  in  paper   67 

18.  COTTON  .  .  .  .  .  .  .     -     .  .  .  .69 

19.  LINEN   70 

20.  an  esparto  duster   74 

21.  Sinclair's  "vomiting"  esparto  boiler    ....  75 

22.  A  PORiON  evaporator   76 

23.  scott's  multiple  effect  evaporator       ....  79 

24.  a  presse-pate  for  esparto  pulp       .....  85 

25.  esparto  pulp   88 

26.  a  cylindrical  digester  for  boiling  fibre      ...  89 

27.  STRAW   93 

P.  b 


X 


LIST  OF  ILLUSTRATIONS 


FIG.  PAGE 

28.  A  PAIR  OF  BARKERS  FOR  REMOVING  BARK  FROM  LOGS  OF  WOOD  98 

29.  VIEW  OF  HORIZONTAL  GRINDER  (a),  WITH  SECTION  (b)   .          .  99 

30.  A  VERTICAL  GRINDER  FOR  MAKING  HOT  GROUND  MECHANICAL 

WOOD  PULP   101 

31.  CENTRIFUGAL  SCREEN  FOR  WOOD  PULP   102 

32.  SECTION  OF  CENTRIFUGAL  SCREEN  FOR  WOOD  PULP         .          .  103 

33.  WOOD    PULP    DIGESTER,    PARTLY    IN    ELEVATION,    PARTLY  IN 

SECTION   106 

34.  VIEW  OF  ORDINARY  SULPHUR-BURNING  OVENS         .          .          .  108 

35.  SPRUCE  WOOD  PULP   114 

36.  MECHANICAL  WOOD  PULP   115 

37.  THE  SCREENS   FOR   REMOVING   COARSE   FIBRES   FROM  BEATEN 

PULP   118 

38.  THE  PAPER  MACHINE   (WET  END   SHOWING  WIRE)  .          .         '.  119 

39.  PAPER  MACHINE   SHOWING  WIRE,  PRESS   ROLLS,  AND  DRYING 

CYLINDERS   123 

40.  SINGLE  CYLINDER  OR  YANKEE  MACHINE           ....  130 

41.  SECTION  OF  WET  PRESS,  OR  BOARD  MACHINE          .          .          .  131 

42.  DOUBLE  CYLINDER  BOARD  MACHINE         ....          .  133 

43.  APPARATUS  FOR  MAKING  PARCHMENT  PAPER  ....  138 

44.  GENERAL  ARRANGEMENT  OF  PLANT  FOR  MAKING  "  ART  "  PAPER  143 

45.  SECTIONAL  ELEVATION  OF  "  COATING  "  PLANT         .          .          .  144 

46.  COTTON  PULP  BEATEN  8  HOURS   179 

47.  COTTON  PULP  BEATEN  37  HOURS   180 

48.  PLAN  AND  SECTIONAL  ELEVATION  OF  A  "HOLLANDER".          .  185 

49.  BEATING  ENGINE  WITH  FOUR  BEATER  ROLLS.          .          .          .  186 

50.  UMPHERSTON;  BEATER   188 

51.  section  of  umpherston  beating  engine  ....  189 

52.  nugent's  beating  engine  with  paddles  for  circulating 

THE  PULP   190 

53.  A  "  TOWER  "  BEATING  ENGINE  WITH  CENTRIFUGAL  PUMP  FOR 

CIRCULATING  PULP                                                                  .          .  191 

54.  WORKING  PARTS  OF  A  MODERN  REFINING  ENGINE  .          .          .  192 

55.  CONVENTIONAL  DIAGRAM   OF  A  WATER  SOFTENING  PLANT        .  216 

56.  AN  "  ENCLOSED  "   STEAM  ENGINE   ......  220 

57.  AN  ELECTRICALLY  DRIVEN  PAPER  MACHINE     ....  222 

58.  DIAGRAM  OF  THE   "  EIBEL  "   PROCESS   223 


THE  MANUFACTURE 
OF  PAPER 


History. — The  art  of  paper-making  is  undoubtedly  one  of 
the  most  important  industries  of  the  present  day.  The 
study  of  its  development  from  the  early  bygone  ages  when 
men  were  compelled  to  find  some  means  for  recording 
important  events  and  transactions  is  both  interesting  and 
instructive,  so  that  a  short  summary  of  the  known  facts 
relating  to  the  history  of  paper  may  well  serve  as  an  intro- 
duction to  an  account  of  the  manufacture  and  use  of  this 
indispensable  article. 

Tradition. — The  early  races  of  mankind  contented  them- 
selves with  keeping  alive  the  memory  of  great  achievements 
by  means  of  tradition.  Valiant  deeds  were  further  com- 
memorated by  the  planting  of  trees,  the  setting  up  of  heaps 
of  stones,  and  the  erection  of  clumsy  monuments. 

Stone  Obelisks. — The  possibility  of  obtaining  greater 
accuracy  by  carving  the  rude  hieroglyphics  of  men  and 
animals,  birds  and  plants,  soon  suggested  itself  as  an 
obvious  improvement ;  and  as  early  as  b.c.  4000  the  first 


CHAPTER  I 


HISTORICAL  NOTICE 


2 


THE  MANUFACTURE  OF  PAPEE 


records  which  conveyed  any  meaning  to  later  ages  were 
faithfully  inscribed,  and  for  the  most  part  consigned  to  the 
care  of  the  priests. 

Clay  Tablets. — The  ordinary  transactions  of  daily  life, 
the  writings  of  literary  and  scientific  men,  and  all  that  was 
worthy  of  note  in  the  history  of  such  nations  as  Chaldea 
and  Assyria  have  come  down  to  us  also,  inscribed  on  clay 
tablets,  which  were  rendered  durable  by  careful  baking. 
On  a  tablet  of  clay,  one  of  the  earliest  specimens  of  writing 
in  existence,  now  preserved  in  the  British  Museum,  is 
recorded  a  proposal  of  marriage,  written  about  b.c.  1530, 
from  one  of  the  Pharaohs,  asking  for  the  hand  of  the 
daughter  of  a  Babylonian  king. 

Waxed  Boards. — Bone,  ivory,  plates  of  metal,  lead,  gold, 
and  brass,  were  freely  used,  and  at  an  early  period  wooden 
boards  covered  with  wax  were  devised  by  the  Komans.  In 
fact,  any  material  having  a  soft  impressionable  surface  was 
speedily  adopted  as  a  medium  for  the  permanent  expression 
of  men's  fancy,  so  that  it  is  not  strange  to  find  instances  of 
documents  written  on  such  curious  substances  as  animal 
skins,  hides,  dried  intestines,  and  leather.  The  works  of 
Homer,  preserved  in  one  of  the  Egyptian  libraries  in  the 
days  of  Ptolemaeus  Philadelphus,  were  said  to  have  been 
written  in  letters  of  gold  on  the  skins  of  serpents. 

Leaves,  Bark. — The  first  actual  advance  in  the  direction  of 
paper,  as  commonly  understood,  was  made  when  the  leaves 
and  bark  of  trees  were  utilised.  The  latter  especially  came 
speedily  into  favour,  and  the  extensive  use  of  the  inner  bark 
{liber)  made  rapid  headway.  Manuscripts  and  documents 
written  on  this  liber  are  to  be  found  in  many  museums. 

Papyrus. — The  discovery  of  the  wonderful  properties  of 
the  Egyptian  papyrus  was  a  great  step  in  developing  the 
art  of  paper-making.  The  date  of  this  discovery  is  very 
uncertain,  but  one  of  the  earliest  references  is  to  be  found 


HISTORICAL  NOTICE 


3 


in  tlie  works  of  Pliny,  where  mention  is  made  of  the  writings 
of  Numa,  who  Hved  about  b.c.  670.  This  celebrated  plant 
had  long  been  noted  for  its  value  in  the  manufacture  of 


•  * 

 -"^"Hr  

Si  J 

tin 

.  !  J».- ST; 

"  Mir 

Fig.  1. — Sheet  of  Papyrus,  showing  the  layers  crossing  one  another 

(Evans). 

mats,  cordage,  and  wearing  apparel,  but  its  fame  rests  upon 
its  utility  in  quite  a  different  direction,  namel}^  for  convey- 
ing to  posterity  the  written  records  of  those  early  days 
which  have  proved  a  source  of  unending  interest  to 
antiquaries. 

B  2 


4 


THE  MANUFACTUEE  OF  PAPER 


The  Egyptian  papyrus  was  made  from  the  fine  layers  of 
fibrous  matter  surrounding  the  parent  stem.  These  layers 
were  removed  by  means  of  a  sharp  tool,  spread  out  on  a 
board,  moistened  with  some  gummy  water,  and  then 
covered  with  similar  layers  placed  over  them  crosswise. 
The  sheets  so  produced  were  pressed,  dried,  and  polished 
with  a  piece  of  ivory  or  a  smooth  stone.  Long  rolls  of 
papyrus  were  formed  by  pasting  several  sheets  together  to 
give  what  was  termed  a  volumen. 

Roman  Papyri. — The  Eomans  improved  the  process  of 
manufacture,  and  were  able  to  produce  a  variety  of  papers, 
to  which  they  gave  different  names,  such  as  Charta  liieratica 
(holy  paper,  used  by  priests),  Charta  Fanniana  (a  superior 
paper  made  by  Fannius),  Charta  emporetica  (shop  or  wrap- 
ping paper),  Charta  Saitica  (after  the  city  of  Sais),  etc.  The 
papyrus  must  have  been  used  in  great  quantities  for  this 
purpose,  since  recent  explorations  in  Eastern  countries  have 
brought  to  light  enormous  finds  of  papyri  in  a  wonderful 
state  of  preservation.  In  1753,  when  the  ruins  of  Hercu- 
laneum  were  unearthed,  no  less  than  1,800  rolls  were 
discovered.  During  the  last  ten  years  huge  quantities  have 
been  brought  to  England. 

Parchment. — Parchment  succeeded  papyrus  as  an  excel- 
lent writing  material,  being  devised  as  a  substitute  for  the 
latter  by  the  inhabitants  of  Pergamus  on  account  of  the 
prohibited  exportation  of  Egyptian  papyrus.  For  many 
centuries  parchment  held  a  foremost  place  amongst  the 
available  materials  serving  the  purpose  of  paper,  and 
even  to-day  it  is  used  for  important  legal  documents.  This 
parchment  was  made  from  the  skins  of  sheep  and  goats, 
which  were  first  steeped  in  lime  pits,  and  then  scraped. 
By  the  plentiful  use  of  chalk  and  pumice  stone  the  colour 
and  surface  of  the  parchment  v>^ere  greatly  enhanced. 
Vellum,  prepared  in  a  similar  manner  from  the  skins  of 


HISTORICAI.  NOTICE 


5 


calves,  was  also  extensively  employed  as  a  writing  material, 
and  was  probably  the  first  material  used  for  binding  books. 
Until  comparatively  recent  times  the  term  parchment  " 
comprehended  vellum,  but  the  latter  substance  is  much 
superior  to  that  manufactured  from  sheep  and  goat  skins. 

Paper. — The  Chinese  are  now  generally  credited  with  the 
art  of  making  paper  of  the  kind  most  famihar  to  us,  that  is 
from  fibrous  material  first  reduced  to  the  condition  of  pulp. 
Materials  such  as  strips  of  bark,  leaves,  and  papyrus  cannot 
of  course  be  included  in  a  definition  like  this,  which  one 
writer  has  condensed  into  the  phrase  "  Paper  is  an  aqueous 
deposit  of  vegetable  fibre." 

A.D.  105. — The  earliest  reference  to  the  manufacture  of 
paper  is  to  be  found  in  the  Chinese  Encyclopedia,  wherein 
it  is  stated  that  Ts'ai-Lun,  a  native  of  Kuei-yang,  entered 
the  service  of  the  Emperor  Ho-Ti  in  a.d.  75,  and  devoting 
his  leisure  hours  to  study,  suggested  the  use  of  silk  and  ink 
as  a  substitute  for  the  bamboo  tablet  and  stylus.  Sub- 
sequently he  succeeded  in  making  paper  from  bark,  tow, 
old  linen,  and  fish  nets  (a.d.  105).  He  was  created  marquis 
in  A.D.  114  for  his  long  years  of  service  and  his  ability. 

A.D.  704. — It  has  been  commonly  asserted  that  raw 
cotton,  or  cotton  wool,  was  first  used  by  the  Arabs  at 
this  date  for  the  manufacture  of  paper,  they  having  learnt 
the  art  from  certain  Chinese  prisoners  captured  at  the 
occupation  of  Samarkand  by  the  Arabs.  The  complete 
conquest  of  Samarkand  does  not,  however,  seem  to  have 
taken  j^lace  until  a.d.  751,  and  there  is  little  doubt  that 
this  date  should  be  accepted  for  the  introduction  of  the  art 
of  paper-making  among  the  Arabs. 

Recent  Researches. — Professors  Wiesner  and  Karabacek 
have  ascertained  one  or  two  most  important  and  inter- 
esting facts  concerning  the  actual  manufacture  of  2)ure 
rag  paper.    In  1877  a  great  quantity  of  ancient  manuscripts 


6 


THE  MANUFACTURE  OP  PAPER 


was  found  at  El-Faijum,  in  Egypt,  comprising  about 
100,000  documents  in  ten  languages,  extending  from  b.c. 
1400  to  A.D.  1300,  many  of  which  were  written  on  paper. 
The  documents  were  closely  examined  in  1894  by  these 
experts,  at  the  request  of  the  owner,  the  Archduke  Kainer 
of  Austria. 

Kesearches  of  a  later  date  resulted  in  the  discovery 
of  some  further  interesting  documents  which  appear  to 
estabhsh  with  some  degree  of  certainty  the  approximate 
date  at  which  pure  rag  paper,  that  is,  paper  made  entirely 
from  rag,  was  manufactured. 

Chinese  documents  dated  a.d.  768 — 786,  which  liave  been 
reported  upon  by  Dr.  Hoernle,  and  others  dated  a.d.  781 — 
782—787,  reported  upon  by  Dr.  Stein  as  recently  as  1901, 
appear  to  show  what  materials  were  used  by  the  Chinese 
paper-makers  in  Western  Turkestan.  The  manuscripts 
mentioned  were  dug  out  from  the  sand-buried  site  of 
Dandan  Uilig,  in  Eastern  Turkestan. 

Professor  Wiesner  found  that  all  the  papers  of  the  Kainer 
collection  were  made  of  linen  rag,  with  an  occasional  trace 
of  cotton,  probably  added  accidentally.  The  earliest  dated 
paper  was  a  letter  a.d.  874,  but  two  documents,  which  from 
other  reasons  could  be  identified  as  belonging  to  a.d.  792, 
proved  that  at  the  end  of  the  eighth  century  the  Arabs 
understood  the  art  of  making  linen  paper  on  network 
moulds,  and  further  that  they  added  starch  for  the  purpose 
of  sizing  and  loading  the  paper. 

Professor  Karabacek  advances  some  ingenious  explana- 
tions as  to  the  origin  of  the  idea  that  raw  cotton  was  first 
used  for  paper-making,  and  he  suggests  that  the  legend  owes 
its  origin  to  a  misunderstanding  of  terms.  In  mediaeval 
times  paper  was  known  as  Charta  homhycina,  and  sometimes 
as  Charta  Damascena,  the  latter  from  its  place  of  origin. 

Paper  was  also  made  in  Bambyce,  and  a  natural  confusion 


HISTOEICAL  NOTICE 


7 


arose  between  the  terms,  since  the  word  homhyx  was  used  as 
a  name  for  cotton,  and  the  paper  commonly  in  use  suggested 
that  material  to  the  mind  of  the  observer,  and  the  name 
became  corrupted  to  homhycina. 

The  suggestions  of  Professor  Karabacek,  together  with 
the  microscopical  investigations  of  Dr.  Wiesner,  appear  to 
show  that  paper  made  entirely  from  raw  cotton  fibre  was 
not  known. 

Invention  of  Rag  Paper. — Dr.  Hoernle,  in  discussing  this 
question,  points  out  that,  taking  a.d.  751  as  the  date  when 
the  Arabs  learnt  the  art  of  paper-making,  and  a.d.  792  as 
the  date  when  paper  made  entirely  of  linen  rag  was  pro- 
duced, the  date  of  the  invention  of  rag  paper  must  lie 
between  these  two  dates.  The  documents  discovered  in 
Eastern  Turkestan  and  bearing  the  dates  mentioned,  which 
papers  fill  up  the  gap  between  the  years  a.d.  751  and 
A.D.  792,  were  found  to  contain  certain  raw  fibres,  such  as 
China  grass,  mulberry,  laurel,  as  the  main  constituents, 
and  macerated  flax  and  hemp  rags  as  the  minor  con- 
stituents. 

The  addition  and  substitution  of  rag  evidently  increased 
in  course  of  time,  and  since  the  improvement  thus  effected 
soon  became  an  obvious  and  established  fact,  the  raw  fibres 
were  omitted.  Hence  the  credit  of  the  manufacture  of  pure 
rag  paper  would  be  given  to  the  people  of  Samarkand,  the 
date  being  between  the  years  a.d.  760  and  a.d.  792  ;  and 
further  the  constitution  of  such  paper  has  been  shown  by 
Dr.  Wiesner  to  be  linen,  and  not  cotton,  as  commonly 
stated. 

These  researches  are  of  such  interest  that  we  quote 
Professor  Hoernle's  translation  of  the  summary  of  the 
principal  results  oc  Dr.  Wiesner's  examination  of  the 
Eastern  Turkestani  papers  so  recently  discovered 

Taking  into  account  the  dates  assigned  to  the  papers  oii 


8 


THE  MANUFACTUEE  OF  PAPEE 


paleeographic  grounds,  the  following  conclusions  may  be 
drawn  from  the  examination  of  their  material : — 

"(1)  The  oldest  of  the  Eastern  Turkestani  papers,  dating 
from  the  fourth  and  fifth  centuries  a.d.,  are  made  of  a 
mixture  of  raw  fibres  of  the  bast  of  various  dicotyledonous 
plants.  From  these  fibres  the  half-stuff  for  the  paper  was 
made  by  means  of  a  rude  mechanical  process. 

"(2)  Similar  papers,  made  of  a  mixture  of  raw  fibres, 
are  also  found  belonging  to  the  fifth,  sixth,  and  seventh 
centuries.  But  in  this  period  there  also  occur  papers 
which  are  made  of  a  mixture  of  rudely  pounded  rags  and 
of  raw  fibres  extracted  by  maceration. 

"  (3)  In  the  same  period  papers  make  their  appearance 
in  which  special  methods  are  used  to  render  them  capable 
of  being  written  on,  viz.,  coating  with  gypsum  and  sizing 
with  starch  or  with  a  gelatine  extracted  from  lichen. 

"  (4)  In  the  seventh  and  eighth  centuries  both  kinds  of 
papers  are  of  equal  frequency,  those  made  of  the  raw  fibre 
of  various  dicotyledonous  plants  and  those  made  of  a  mixture 
of  rags  and  raw  fibres.  In  this  period  the  method  of  extract- 
ing the  raw  fibre  is  found  to  improve  from  a  rude  stamping 
to  maceration  ;  but  that  of  j^reparing  the  rags  remains  a 
rude  stamping,  and  in  the  half-stuff  thus  produced  from 
rags  it  is  easy  to  distinguish  the  raw  fibre  from  the  crushed 
and  broken  fibre  of  the  rags. 

"  (5)  The  old  Eastern  Turkestani  (Chinese)  paper  can  be 
distinguished  from  the  old  Arab  paper,  not  only  by  the  raw 
fibres  which  accompany  the  rag  fibres,  but  also  by  the  far- 
reaching  destruction  of  the  latter. 

"  (6)  The  previous  researches  of  Professor  Karabacek  and 
the  author  had  shown  that  the  invention  of  rag  paper  was 
not  made  in  Europe  by  Germans  or  Italians  about  the  turn 
of  the  fourteenth  century,  but  that  the  Arabs  knew  its 
preparation  as  early  as  the  end  of  the  eighth  century. 


HISTOEICAL  NOTICE 


"  The  present  researches  now  further  show  that  the 
beginnings  of  the  preparation  of  rag  paper  can  be  traced 
to  the  Chinese  in  the  fifth  or  fourth  centuries,  or  even 
earher. 

"  The  Chinese  method  of  preparing  rag  paper  never  pro- 
gressed beyond  its  initial  low  stage.  It  was  the  Arabs  who, 
having  been  initiated  into  the  art  by  the  Chinese,  improved 
the  method  of  preparing  it,  and  carried  it  to  that  stage  of 
perfection  in  which  it  was  received  from  them  by  the 
civilised  peoples  of  Europe  in  the  mediaeval  ages. 

"  (7)  The  author  has  shown  that  the  process  of  sizing  the 
paper  with  starch  in  order  to  improve  it  was  already  known 
to  the  Arabs  in  the  eighth  century.  In  the  fourteenth 
century  the  knowledge  of  it  was  lost,  animal  glue  being 
substituted  in  the  place  of  starch,  till  finally  in  the  nine- 
teenth century,  along  with  the  introduction  of  paper 
machines,  the  old  process  was  resuscitated.  But  the  inven- 
tion of  it  was  due  to  the  Chinese.  The  oldest  Eastern 
Turkestani  paper  which  is  sized  with  starch  belongs  to  the 
eighth  century. 

"  (8)  The  Chinese  were  not  only  the  inventors  of  felted 
paper  and  the  imitators  of  rag  paper — though  in  the  pre- 
paration of  the  latter  they  made  use  of  rags  only  as  a 
surrogate  by  the  side  of  raw  fibres — but  they  must  also  be 
credited  with  being  the  forerunners  of  the  modern  method 
of  preparing  *  cellulose  paper.'  For  their  very  ancient 
practice  of  extracting  the  fibre  from  the  bark  and  other 
parts  of  plants  by  means  of  maceration  is  in  principle 
identical  with  the  modern  method  of  extracting  '  cellulose  ' 
by  means  of  certain  chemical  processes." 

Paper-making  in  Europe. — The  introduction  of  the  art 
into  Europe  seems  to  have  taken  place  early  in  the  eleventh 
century,  when  the  Moors  manufactured  paper  at  Toledo. 
The  early  authorities  who  have  studied  this  subject  express 


10 


THE  MANUFACTUEE  OF  PAPER 


YiQ,  2.— An  Early  Paper  Mill  (from  "  Kulturhistorischen  Bilderbuch," 

A.D.  lo6t). 


HISTOEICAL  NOTICE 


11 


the  opinion  that  the  paper  produced  in  Europe  at  this 
time  was  made  from  cotton  rags  and  from  raw  cotton, 
but,  in  view  of  the  recent  researches  into  the  composition  of 
paper,  it  is  difBcult  to  say  how  this  idea  arose,  unless  we 
accept  the  explanation  offered  by  Professor  Karabacek.  In 
standard  encyclopgedias  the  following  statements  are  made 
as  to  existing  early  documents  printed  on  paper  made  in 
Europe : — 

A.D.  1075.  Syriac  manuscripts  of  early  date  in  the  British 
Museum. 

A.D.  1102.  A  document  printed  on  cotton,  being  a  deed 
of  King  Eoger  of  Sicily,  now  at  Vienna. 

A.D.  1178.  A  treaty  of  peace  between  the  Kings  of 
Aragon  and  Spain,  said  to  be  printed  on 
linen  paper,  preserved  at  Barcelona. 

A.D.  1223.  The  "Liber  Plegierum,"  printed  on  rough 
cotton  paper. 

One  of  the  most  interesting  books  on  this  subject  is  the 
"  Historical  Account  of  the  Substances  used  to  describe 
Events  from  the  Earliest  Date,"  by  Matthias  Koops,  i^ub- 
lished  in  1800.  This  writer  appears  to  have  obtained  most 
of  his  information  from  German  authorities. 

The  industry  of  paper-making  passed  through  Spain 
into  Italy,  France,  and  the  Netherlands.  In  1189  paper 
was  being  manufactured  at  Hainault,  in  France,  and  the 
industry  rapidly  spread  all  over  the  Continent.  In  1390 
Ulman  Stromer  established  a  mill  at  Nuremberg,  in  Ger- 
many, employing  a  great  number  of  men,  who  were  obliged 
to  take  an  oath  that  they  would  not  teach  anyone  the  art 
of  paper-making  or  make  paper  on  their  ow^n  account.  In 
the  sixteenth  century  the  Dutch  endeavoured  to  protect 
their  industry  by  making  the  exportation  of  moulds  for 
paper-making  an  offence  punishable  by  death. 


12 


THE  MANUFACTUEE  (3F  PAPEE, 


The  bulk  of  the  paper  used  in  England  was  imported 
from  France  and  Holland,  and  it  was  many  years  before 
the  industry  was  established  in  England.    This  is  not  sur- 


PiG.  3.— The  Paper  Mill  of  Ulman  Stromer,  a.d.  1390  (supposed  to  be 
the  oldest  known  drawing  of  a  Paper  Mill}. 


prising  in  view  of  the  protective  and  conservative  policy  of 
the  Continental  paper-makers. 

Paper-making  in  England. — The  actual  period  at  which 
the  manufacture  of  paper  was  first  started  in  England  is 
somewhat  uncertain.  The  first  mention  of  any  paper-maker 
is   found   in  Wynkyn   de  Worde's   "  De  Proprietatibus 


HISTOEICAL  NOTICE 


13 


Keriim,"  printed  by  Caxton  in  1495,  the  reference  being  as 
follows : — 

And  John  Tate  the  younger,  joye  mote  he  brok, 
Which  late  hathe  in  England,  doo 
Make  thys  paper  thynne, 
That  now  in  our  Englyssh 
.  Thys  booke  is  prynted  inne. 

John  Tate  was  the  owner  of  a  mill  at  Stevenage,  Hertford- 
shire. In  the  household  book  of  Henry  YII.  an  entry  for 
the  year  1499  reads,  "  Geven  in  rewarde  to  Tate  of  the 
mylne,  6s.  8d." 

In  1588  a  paper  mill  was  erected  by  Sir  John  Spielman, 
a  German,  who  obtained  a  licence  from  Queen  Elizabeth 
"for  the  sole  gathering  for  ten  years  of  all  rags,  etc., 
necessary  for  the  making  of  paper."  This  paper  mill  was 
eulogised  by  Thomas  Churchyard  in  a  long  poem  of  forty- 
four  stanzas,  of  which  we  quote  two : — 

I  prayse  the  man  that  first  did  paper  make, 
The  only  thing  that  sets  all  virtues  forth ; 

It  shoes  new  bookes,  and  keeps  old  workes  awake, 
Much  more  of  price  than  all  the  world  is  worth  : 

It  witnesse  bears  of  friendship,  time,  and  troth. 

And  is  the  tromp  of  vice  and  virtue  both  ; 

Without  whose  help  no  hap  nor  wealth  is  won. 

And  by  whose  ayde  great  works  and  deedes  are  done. 

Six  hundred  men  are  set  to  worke  by  him 

That  else  might  starve,  or  seeke  abroad  their  bread, 

Who  now  live  well,  and  goe  full  brave  and  trim. 
And  who  may  boast  they  are  with  paper  fed. 

Strange  is  that  foode,  yet  stranger  made  the  same, 

For  greater  help,  I  gesse,  he  cannot  give 

Than  by  his  help  to  make  poore  folk  to  live. 

The  industry  made  but  little  progress  for  some  time  after 
Spielman's  death,  and  up  till  1670  the  supplies  of  paper 
were  obtained  almost  entirely  from  France.  The  first 
British  patent  for  paper-making  was  granted  to  Charles 


14 


THE  MANUFACTUEE  OF  PAPEE 


Hildeyard  in  1665  for  "  the  way  and  art  of  making  blue 
paper  used  by  sugar  bakers  and  others."  The  trade 
received  a  great  impetus  on  account  of  the  presence  of 
Huguenots  who  had  fled  to  England  from  France  in  con- 
sequence of  the  revocation  of  the  edict  of  Nantes  in  1685. 

In  1695  a  company  was  formed  in  Scotland  for  the 
"  manufacture  of  white  and  printing  paper." 

Improvements  in  the  art  were  slow  until  1760,  when 
Whatman,  whose  name  has  since  become  famous  in  connec- 
tion with  paper,  commenced  operations  at  Maidstone. 
Meantime  the  methods  by  which  the  rags  were  converted 
into  paper  were  exceedingly  slow  and  clumsy,  so  that  the 
output  of  finished  paper  was  very  small. 

Some  interesting  details  as  to  the  early  manufacture  of 
paper  in  England  are  given  by  Mr.  Ehys  Jenkins,  and  from 
his  account  of  "Early  Attempts  at  Paper-making  in 
England,  1495—1788,"  the  following  extracts  have  been 
made : — 
About 

1496.  First  attempts  at  paper-making  by  John  Tate  at  Hertford. 
1496.  Tate's  paper  used  by  Wynkyn  de  Worde  in  "  De  Proprietatibus 
Eerum." 

1557.  A  paper  mill  in  existence  at  Fenditton,  Cambridge. 
1569.  A  mill  at  Bemmarton,  Wilts. 

1574.  Mill  erected  at  Osterley,  Middlesex,  by  Sir  Thomas  Gresham. 
1585.  Eichard  Tottyl  asked  for  sole  rigbt  to  make  paper  for  thirty- 
one  years,  which  was  not  granted. 
1588.  John  Spilman  erected  a  mill  at  Dartford,  Kent.    Granted  a 

patent  for  sole  manufacture  of  paper. 
1588.  Churchyard's  poem  on  the  "Paper  Myll  built  near  Darthford  by 

Master  Spilman." 
1612.  Eobert  Heyricke's  mill  at  Cannock  Chase,  Staffordshire. 
1636.  The  three  or  four  paper  mills  in  the  neighbourhood  of  Hounslow 

and  Colnbrook  temporarily  shut  down  on  account  of  the  plague, 

the  collection  of  rags  having  been  forbidden. 
1665.  Patent  granted  to  Charles  Hildeyard  for  an  invention,  "  the  way 

and  art  of  making  blew  paper  used  by  sugar  bakers  and 

others." 


HISTOEICAL  NOTICE 


15 


About 

1675.  Approximate  date  of  erection  of  mills  at  Wolvercote,  Oxford, 

where  the  Oxford  India  paper  is  now  made. 
1678.  Mill  at  Byfleet,  Surrej%  mentioned  by  Evelyn  in  his  diary. 
1682.  Bladen — A  patent  for  an  engine  and  process  whereby  rags  are 

wrought  into  paper. 
1684.  Baysmaker — A  patent  for  "the  art  and  mistery  of  making  paper 

in  whole  sheets." 

1684.  Jackson — A  patent  for  "  an  engine,  either  for  wind  or  water,  which 
prepareth  all  materials  whereof  paper  may  be  made."  Evi- 
dently Jackson  was  acquainted  with  the  "Hollander"  beating 
engine. 

1686.  A  charter  granted  to  the  "White  Paper  Makers'  Company  "  for 
the  sole  right  of  making  paper  exceeding  4s.  a  ream  in  value. 

1674.  Annual  importation  of  paper,  presumably  from  France,  stated  to 
be  160,000  reams,  of  average  value  of  os.  (Somers). 

1689.  Trade  with  France  prohibited  by  royal  proclamation. 

1696.  Price  of  paper  very  high  owing  to  scarcity,  being  lis.  per 
ream. 

1712.  Duties  levied  on  all  kinds  of  paper,  manufactured  or  imported. 
1725.  Monopoly  of  making  paper  for  Bank  of  England  notes  granted 

to  De  Portal,  of  the  Laverstoke  mills,  Hampshire.    This  paper 

is  still  made  by  the  firm  of  Messrs.  Portal. 
1739.  Galliott  and  Parry  estimated  that  there  were  600  paper  mills  in 

England,  making  6,000  reams  a  day.    The  Commissioner  of 

Excise  reported  only  278. 
1739.  James  Whatman  erected  a  mill  at  Boxley,  Maidstone. 
1758.  Baskerville  printed  an  edition  of  Virgil  on  so-called  "  woven  " 

paper. 

Early  Methods. — Tlie  most  rapid  development  of  the 
industry  appears  to  have  taken  place  in  Holland.  The  rags 
used  for  paper-making  were  moistened  with  water  and 
stored  up  in  heaps  until  they  fermented  and  became  hot. 
By  this  means  the  dirt  and  non-fibrous  matter  was  rendered 
partially  soluble,  so  that  on  washing  a  suitable  paper  pulp 
was  obtained.  The  washed  rags  were  then  placed  in  a 
stamping  machine  resembling  an  ordinary  pestle  and 
mortar.  The  mortars  were  constructed  of  stone  and  wood, 
and  the  stamps  were  kept  in  motion  by  levers  which  were 


16 


THE  MANUFACTURE  OE  PAPER 


raised  by  projections  fixed  on  the  shaft  of  a  water  wheel. 
The  operation  of  beating  thus  occupied  a  long  period,  but 
the  paper  produced  was  of  great  strength. 

The  invention  of  the  "Hollander,"  a  simple  yet  inge- 
nious engine  which  is  deservedly  known  by  the  name  of  the 
country  in  which  it  first  originated,  gave  a  tremendous 
impetus  to  the  art  of  paper-making,  as  by  its  means  the 
quantity  of  material  which  could  be  treated  in  twenty-four 
hours  was  greatly  increased.  Unfortunately  the  date  of 
the  invention  of  this  important  machine  has  not  been 
definitely  traced.  The  earliest  mention  of  it  seems  to  occur 
in  Sturm's  "  Vollstandige  Muhlen  Baukunst,"  published  in 
1718.  It  was  in  extensive  use  at  Saardam  in  1697,  so  that 
the  invention  is  at  least  some  years  previous  to  1690. 

On  this  point  Koops  says:  *'In  Gelderland  are  a  great 
many  mills,  but  some  so  small  that  they  are  only  able 
to  make  400  reams  of  paper  annually,  and  there  are 
also  water  mills  with  stampers,  like  those  in  Germany. 
But  in  the  province  of  Holland  there  are  windmills,  with 
cutting  and  grinding  engines,  which  do  more  in  two  hours 
than  the  others  do  in  twelve.  In  Saardam  1,000  persons 
are  employed  in  paper-making." 

The  First  Fourdrinier  Paper  Machine. 

Up  till  the  year  1799  paper  was  made  entirely  in  sheets 
on  a  hand  mould,  but  during  the  last  few  years  of  the 
eighteenth  century  a  Frenchman,  Nicholas  Louis  Robert, 
manager  for  M.  Didot,  who  owned  a  paper  mill  at 
Essones,  had  been  experimenting  for  the  purpose  of  making 
paper  in  the  form  of  a  continuous  sheet,  and  eventually 
produced  some  of  considerable  length. 

The  idea  was  taken  to  England  by  Didot's  brother-in-law, 
Gamble,  and  introduced  to  the  notice  of  Messrs.  Fourdrinier, 
wholesale  stationers,  of  London. 


HISTOEICAL  NOTICE 


17 


The  first  machine  was  naturally  a  very  crude  affair.  It 
consisted  of  an  endless  wire  cloth  stretched  in  a  horizontal 


Fig.  4.— The  First  Paper  Machine,  A.D.  1802.    Plan  and  Elevation. 

position  on  two  rollers,  one  of  which  rotated  freely  in  a 
bearing  attached  to  the  frame  of  the  machine,  the  other 
being  fitted  in  an  adjustable  bearing  so  that  the  wire  could 
be  tightened  up  when  necessary. 

p.  c 


18 


THE  MANUFACTURE  OF  PAPER 


The  beaten  pulp,  contained  in  a  vat  placed  below  the 
wire,  was  thrown  up  in  a  continual  stream  upon  the  surface 
of  the  wire,  and  carried  forward  towards  the  squeezing  rolls. 
A  shaking  motion  was  imparted  to  the  travelling  wire  so  as 
to  cause  the  fibres  to  felt  properly.  A  great  deal  of  the 
water  fell  through  the  meshes  of  the  gauze,  and  further 
quantities  were  removed  by  means  of  the  press  rolls.  The 
wet  paper  was  then  wound  up  on  to  a  wooden  roller,  which 
was  taken  out  as  soon  as  sufficient  paper  had  been  made. 

The  whole  process  was  carried  on  under  great  difficulties, 
but  substantial  improvements  were   soon  made  by  the 


Fig.  5. — Tlie  Improved  Paper  Machine  of  a.d.  1810. 

enterprising  Fourdriniers,  who  commenced  operations  in 
Bermondsey,  employing  Mr.  Bryan  Donkin,  then  in  the 
service  of  Messrs.  Hall  &  Co.,  of  Dartford,  who  had 
shown  himself  keenly  interested  in  the  machine.  In  1803 
the  first  "  Fourdrinier,"  so  called,  was  built  at  Bermondsey, 
and  erected  at  Two  Waters  Mill  in  Herefordshire. 

In  this  machine  the  mixture  of  pulp  and  water  was 
carried  forward  between  two  wires,  and,  after  passing  through 
the  couch  rolls,  transferred  to  an  endless  felt.  This 
arrangement  proved  to  be  faulty  because  the  water  did  not 
escape  freely  enough  from  the  wire,  and  a  great  deal  of  the 
paper  was  spoilt. 


HISTORICAL  NOTICE 


19 


Donkin,  however,  hit  upon  a  simple  but  effective  device 
for  curing  this  fault  by  altering  the  relative  position  of  the 
two  couch  rolls.  Instead  of  keeping  the  two  rolls  exactly  in 
a  vertical  position  one  over  the  other,  he  placed  them  at  a 
slight  angle  so  that  the  upper  one  should  bear  gently  on 
the  web  of  paper  carried  by  the  wire  before  receiving  the 
full  pressure  of  the  rolls,  and  thus  remove  a  greater  pro- 
portion of  the  water.  In  this  way  the  paper  was  firmer 
and  less  liable  to  break  when  pressed  between  the  couch 
rolls,  an  additional  advantage  being  secured  in  the  fact  that 
the  upper  wire  could  be  dispensed  with. 

The  various  improvements  effected  resulted  in  a  machine 
the  details  of  which  appear  in  the  appended  diagram,  the 
device  of  the  inclined  couch  rolls  being  fitted  about  1810. 

The  mixture  of  water  and  pulp  flowed  from  a  stuff  chest 
into  a  small  regulating  box  and  on  to  the  wire  over  a 
sloping  board.  The  pulp  at  once  formed  into  a  wet  sheet 
of  paper,  the  water  falling  through  the  meshes  of  the  wire, 
being  caught  in  a  bucket-shaped  appliance,  and  conveyed 
back  to  the  regulating  box.  The  stream  of  palp  was 
confined  upon  the  wire  by  means  of  a  deckle.  Further 
quantities  of  water  were  removed  by  the  aid  of  a  pair  of 
squeezing  rolls  before  the  web  passed  through  the  couch- 
rolls,  after  which  the  paper  was  reeled  up  on  a  wooden 
spindle. 

From  this  date  the  success  of  the  machine  was  assured, 
though  the  inventor  and  his  colleagues  were  practically 
ruined,  an  experience  only  too  common  with  the  early 
pioneers  of  many  great  and  useful  industrial  enterprises. 
In  fact,  the  firm  of  Messrs.  Donkin  were  the  only  people  to 
profit  from  the  invention,  for  they  manufactured  a  number 
of  machines,  as  stated  in  the  report  of  the  Jurors  of  the 
Exhibition  of  1851,  and  from  1803  to  1851  no  less  than  190 
Fourdrhiiers  were  set  to  work. 

c  2 


CHAPTEE  II 


CELLULOSE  AND  PAPER-MAKING  FIBRES 

When  plants  such  as  flax,  cotton,  straw,  hemp,  and  other 
varieties  of  the  vegetable  kingdom  are  digested  with  a 
solution  of  caustic  soda,  washed,  and  then  bleached  by 
means  of  chloride  of  lime,  a  fibrous  mass  is  obtained  more 
or  less  white  in  colour. 

This  is  the  substance  known  to  paper-makers  as  paper 
pulp,  and  the  several  modifications  of  it  derived  from 
different  plants  are  generally  known  to  chemists  as 
cellulose. 

Although  plants  differ  greatly  in  physical  structure  and 
general  appearance,  yet  they  all  contain  tissue  which  under 
suitable  treatment  yields  a  definite  proportion  of  this  fibrous 
substance.  The  preparation  of  a  small  quantity  of  cellulose 
from  materials  like  straw,  rope,  hemp,  the  stringy  bark  of 
garden  shrubs,  wood,  and  bamboo  can  easily  be  accomplished 
without  special  appliances.  Soft  materials,  such  as  straw 
and  hemp,  are  cut  up  into  short  pieces,  hard  substances  like 
wood  and  bamboo  are  thoroughly  hammered  out,  in  order 
to  secure  a  fine  subdivision  of  the  mass.  The  fibre  so  pre- 
pared is  then  placed  in  a  small  iron  saucepan,  and  covered 
with  a  solution  made  up  of  ten  parts  of  caustic  soda  and 
100  parts  of  water.  The  material  is  boiled  gently  for  eight 
or  ten  hours,  the  water  which  is  lost  through  evaporation 
of  steam  being  replaced  by  fresh  quantities  of  hot  water  at 
regular  intervals.  When  the  fibrous  mass  breaks  up  readily 
between  the  fingers,  it  is  poured  into  a  sieve,  or  on  a  piece 


CELLULOSE  AND  PAPEE-MAKING  FIBEES  21 


of  muslin  stretched  over  a  basin,  and  washed  completely 
with  hot  water  until  clean  and  free  from  alkali.  Hard 
pieces  and  portions  which  seem  incompletely  boiled  are 
removed,  and  the  residual  fibres  separated  out.  These 
fibres  are  placed  in  a  weak,  clear  solution  of  ordinary 
bleaching  powder,  left  for  several  hours,  and  subsequently 
thoroughly  washed.  This  simple  process  will  give  a  more  or 
less  white  fibrous  material. 

The  purest  form  of  cellulose  is  cotton.  A  very  slight 
alkaline  treatment,  followed  by  bleaching,  is  sufficient  to 
remove  the  non-fibrous  constituents  of  the  plant,  and  a 
large  yield  of  cellulose  is  obtained.  For  this  reason  the 
cotton  fibre  ranks  high  as  an  almost  ideal  material  for 
paper-making,  possessing  the  quality  of  durability. 

Cellulose  is  an  organic  compound,  containing  carbon, 
hydrogen,  and  oxygen  in  the  following  proportions: — 


Its  composition  is  represented  by  the  formula  Ce  Hio  O5. 

The  celluloses  obtained  from  various  plants  are  not 
identical  either  in  physical  structure  and  chemical  constitu- 
tion, or  as  to  their  behaviour  w^hen  employed  for  paper- 
making.  In  fact,  the  well-known  differences  between  the  raw 
materials  used  for  paper-making,  and  also  between  the 
numerous  varieties  of  finished  paper,  are  to  be  largely 
accounted  for  and  explained  by  a  careful  study  of  the 
cellulose  group,  particularly  w  ith  reference  to  the  microscopic 
characteristics  and  the  chemical  composition  of  the  individual 
species. 

The  only  vegetable  substance  which  may  be  regarded  as 


Carbon 
Hydrogen  . 
Oxygen  . 


44-2 
6-8 
49-5 


100-0 


22 


THE  MANUFACTURE  OF  PAPER 


a  simple  cellulose  is  cotton,  all  others  being  compound 
celluloses  of  varying  constitution,  the  nature  of  which 
cannot  be  appreciated  without  a  considerable  knowledge  of 
chemistry.  The  classification  of  such  plants,  therefore,  in 
a  book  of  this  description  must  be  limited  to  certain  dis- 
tinctions having  some  immediate  practical  bearing  on  the 
question  of  paper  manufacture. 

Cotton. — Kegarded  as  the  typical  simple  cellulose,  contain- 
ing 91  per  cent,  of  cellulose,  and  remarkable  for  its  resistance 
to  the  action  of  caustic  soda. 

Linen. — The  cellulose  isolated  from  flax  by  treatment 
with  alkali  or  caustic  soda  cannot  readily  be  distinguished 
from  cotton  cellulose  by  chemical  analysis  or  reactions. 
The  difference  is  almost  entirely  a  physical  one. 

Flax  is  a  typical  compound  cellulose,  to  which  has  been 
given  the  name  pecto-cellulose  on  account  of  certain  pro- 
perties. Other  well-known  plants  of  this  class  are  ramie, 
aloe,  "  sunn  hemp,"  manila. 

Esjmrto. — The  cellulose  isolated  from  esparto  differs  in 
composition  from  cotton  cellulose  : — 


It  is  regarded  as  an  oxy cellulose,  being  readily  oxidised 
by  exposure  to  air  at  100°  C.  Other  oxycelluloses  familiar 
to  the  paper-maker  are  straw,  sugarcane,  bamboo. 

Wood. — The  difference  between  wood  and  the  plants 
already  mentioned  is  expressed  by  the  term  lignified 
fibre  or  ligno-cellulose.  This  term  is  used  to  indicate  that 
the  wood  is  a  compound  cellulose  containing  non-fibrous 


Carbon 

Hydrogen 

Oxygen 


41-0 
5-8 
53-2 


100-0 


CELLULOSE  AND  PAPER-MAKING  FIBEES  23 


constituents,  to  which  has  been  given  the  name  lignone. 
Jute  is  another  example  of  this  class. 

These  distinctions  may  be  exemplified  by  reference  to  a 
simple  experiment.  If  three  papers,  such  as  a  pure  rag 
tissue  or  a  linen  writing,  an  ordinary  esparto  printing,  and  a 
cheap  newspaper  containing  about  80  per  cent,  of  mechanical 
wood,  are  heated  for  twenty-four  hours  in  an  oven  at  a 
temperature  of  105^  C,  the  first  will  undergo  little,  if  any, 
change  in  colour,  while  the  others  will  be  appreciably 
discoloured,  the  mechanical  wood  pulp  paper  most  of  all. 

This  change  is  due  to  the  gradual  oxidation  of  the  con- 
stituents of  the  paper,  the  ligno-cellulose  of  the  mechanical 
wood  pulp  being  most  readily  affected  by  the  high  tempera- 
ture, and  the  pure  cellulose  of  the  rag  paper  being  least 
altered. 

The  process  of  oxidation,  brought  about  rapidly  under  the 
conditions  of  the  experiment  described,  takes  place  in  papers 
of  low  quality  exposed  to  air  in  the  ordinary  circumstances 
of  daily  use,  but  of  course  at  an  extremely  slow  rate.  The 
deterioration  of  such  paper  is  not,  however,  due  to  the  simple 
oxidation  of  the  cellulose  compounds,  because  other  factors 
have  to  be  taken  into  account.  The  presence  of  impurities 
in  the  paper  on  the  one  hand,  and  of  chemical  vapours  in 
the  air  on  the  other,  hastens  the  decay  of  papers  very 
considerably. 

Percentage  of  Cellulose  in  Fibrous  Plants. — The  value  of 
a  vegetable  plant  for  paper-making  is  first  determined  by  a 
close  examination  of  the  physical  structure  of  the  cellulose 
isolated  by  the  ordinary  methods  of  treatment.  If  the 
fibres  are  weak  and  short,  the  raw  material  is  of  little 
value,  and  it  is  at  once  condemned  without  further  inves- 
tigation, but  should  the  fibre  prove  suitable,  then  the 
question  of  the  percentage  of  cellulose  becomes  important. 


24 


THE  MA.NUFACTUEE  OF  PAPER 


There  are  several  methods  employed  for  estimating  the 
amount  of  cellulose  in  plants.  The  process  giving  a 
maximum  yield  is  known  as  the  chlorination  method,  the 
details  of  which  are  as  follows  : — About  ten  grammes  of  the 
air-dried  fibre  is  dried  at  100°  C.  in  a  water  oven  for  the 
determination  of  moisture.  A  second  ten  grammes  of  the 
air- dried  fibre  is  boiled  for  thirty  minutes  with  a  weak  solution 
of  pure  caustic  soda  (ten  grammes  of  caustic  soda  in  1,000 
cubic  centimetres  of  water),  small  quantities  of  distilled 
water  being  added  at  frequent  intervals  to  replace  water 
lost  by  evaporation.  The  residue  is  then  poured  on  to  a 
piece  of  small  wire  gauze,  washed  thoroughly,  and  squeezed 
out.  The  moist  mass  of  fibre  is  loosened  and  teased  out, 
placed  in  a  beaker,  and  submitted  to  the  action  of  chlorine 
gas  for  an  hour.  The  bright  yellow  mass  is  then  washed 
with  water  and  immersed  in  a  solution  of  sodium  sulphite 
(twenty  grammes  of  sodium  sulphite  in  1,000  cc.  of 
water).  The  mixture  is  slowly  heated,  and  finally  boiled 
for  eight  to  ten  minutes,  with  the  addition  of  10  cc. 
of  caustic  soda  solution.  The  residue  is  washed,  immersed 
in  dilute  sodium  hypochlorite  solution  for  ten  minutes, 
again  washed,  first  with  water  containing  a  little  sulphurous 
acid  and  then  with  pure  distilled  water.  It  is  finally  dried 
and  weighed. 

The  second  process  for  estimating  cellulose  is  based  upon 
the  use  of  bromine  and  ammonia.  About  ten  grammes  of  the 
air-dried  fibre  is  placed  in  a  well-stoppered  wide-mouthed 
bottle  with  sufficient  bromine  water  to  cover  it.  As  the 
reaction  proceeds  the  red  solution  gradually  decolourises, 
and  farther  small  additions  of  bromine  are  necessary.  The 
mass  is  then  washed,  and  boiled  in  a  flask  connected  to  a 
condenser  with  a  strong  solution  of  ammonia  for  about 
three  to  four  hours.  The  fibrous  residue  is  washed,  again 
treated  with  bromine  water  in  the  cold,  and  subsequently 


CELLULOSE  AND  PAPER-MAKING  FIBRES 


25 


boiled  with  ammonia.  The  alternative  treatment  with 
bromine  and  ammonia  is  repeated  until  a  white  fibrous 
mass  is  obtained. 

In  practice  the  paper-maker  is  confined  to  two  or  three 
methods  for  the  isolation  of  the  fibres,  viz.,  alkaline  pro- 
cesses, which  require  the  digestion  of  the  material  with 
caustic  soda,  lime,  lime  and  carbonate  of  soda,  chiefly 
applied  to  the  boiling  of  rags,  esparto,  and  similar  pecto- 
celluloses  ;  acid  processes,  in  which  the  material  is  digested 
with  sulphurous  acid  and  sulphites.  The  latter  methods 
are  at  present  almost  exchisively  used  for  the  preparation 
of  chemical  wood  pulp. 

Yields  of  Cellulose  in  the  Paper  Mill. — The  object  of  the 
paper-maker  is  to  obtain  a  maximum  yield  of  cellulose 
residue  at  a  minimum  of  cost.  Usually  the  amount  of 
actual  bleached  paper  pulp  obtained  in  the  mill  is  less  than 
the  percentage  obtained  by  careful  quantitative  analysis, 
for  reasons  easily  understood. 

In  the  first  place,  the  raw  material  is  digested  for  a  stated 
period  with  a  carefully  measured  quantity  of  caustic  soda, 
for  example,  at  a  certain  temperature.  Now  the  conditions 
of  boiling  may  be  varied  by  altering  one  or  more  of  these 
factors,  the  period  of  boiling,  the  strength  of  solution,  or 
the  steam  pressure,  and  the  paper-maker  must  exercise  his 
judgment  in  fixing  the  exact  relation  between  the  varying 
factors  so  as  to  produce  the  best  results. 

In  the  second  place,  the  mechanical  devices  for  washing 
the  boiled  pulp  and  for  bleaching  cause  slight  losses  of 
fibre,  which  cannot  be  altogether  avoided  when  operations 
are  conducted  on  a  large  scale.  Frequently,  also,  a  greater 
yield  of  boiled  material  may  involve  a  larger  quantity  of 
bleaching  powder,  so  that  it  is  evident  the  adjustment  of 
practical  conditions  requires  considerable  technical  skill  and 
experience. 


26 


THE  MANUFACTURE  OF  PAPER 


The  percentage  of  cellulose  in  the  vegetable  plants 
employed  more  or  less  in  the  manufacture  of  paper  is  given 
in  the  following  table  : — 

Table  showing  Percentage  of  Cellulose  in  Fibrous  Plants. 


Fibre. 

Cellulose,  per  cent. 

Cotton 

91-0 

Flax 

82-0 

Hemp 

77-0 

Ramie 

76-0 

Manila 

64-0 

Jute 

64-0 

Wood  (pine) 

57-0 

Bagasse 

oO-O 

Bamboo 

48-0 

Esparto 

48  to  42 

Straw 

48  to  40 

The  Properties  of  Cellulose.  —  Cellulose  is  remarkably 
inert  towards  all  ordinary  solvents  such  as  water,  alcohol, 
turpentine,  benzene,  and  similar  reagents,  a  property  which 
renders  it  extremely  useful  in  many  industries,  with  the 
result  that  the  industrial  applications  of  cellulose  are 
numerous  and  ^exceedingly  varied. 

Solubility. — Cellulose  is  dissolved  when  brought  into  con- 
tact with  certain  metallic  salts,  but  it  behaves  quite  diffe- 
rently to  ordinary  organic  compounds.  Sugar,  for  example, 
is  a  crystalline  body  soluble  in  water,  and  can  be  recovered 
in  a  crystalline  state  by  gradual  evaporation  of  the  water. 
Cellulose  under  suitable  conditions  can  be  dissolved,  but  it 
cannot  be  reproduced  in  structural  form  identical  with  the 
original  substance. 

If  cellulose  is  gently  heated  in  a  strong  aqueous  solution 
of  zinc  chloride,  it  gradually  dissolves,  a  thick  syrupy  mass 
being  obtained,  which  consists  of  a  gelatinous  solution  of 


CELLULOSE  AND  PAPEE-MAKING  FIBRES  27 


cellulose.  If  the  mixture  is  diluted  with  cold  water,  a  pre- 
cipitate is  produced  consisting  of  cellulose  hydrate  intimately 
associated  with  oxide  of  zinc,  which  latter  can  be  dissolved 
out  by  means  of  hydrochloric  acid.  The  resulting  product 
is  not,  however,  the  original  substance,  but  a  hydrated 
cellulose,  devoid  of  any  crystalline  structure. 

Cellulose  is  also  soluble  in  ammoniacal  solutions  of  cupric 
oxide,  from  which  it  can  be  precipitated  by  acids  or  by 
substances  which  act  as  dehydrating  agents,  e.g.,  alcohol. 

Hi/drolijsis. — An  explanation  of  the  behaviour  of  cellulose 
towards  the  solvents  already  mentioned,  and  towards 
acid  and  alkali,  requires  a  reference  to  its  chemical 
composition. 

The  substance  is  a  compound  of  carbon,  hydrogen,  and 
oxygen  represented  by  the  formula 

Cg  Hio  O5 

being  one  of  a  class  of  organic  compounds  known  as  carbo- 
hydrates, so  designated  because  the  hydrogen  and  oxygen 
are  present  in  the  proportions  which  exist  in  water. 

Water  =  Hydrogen  +  Oxygen 
H2  4-  0. 

The  Hio  O5  in  the  cellulose  formula  corresponds  to 
5  (H2  0). 

When  cellulose  is  acted  upon  by  acid,  alkali,  and  certain 
metallic  salts,  it  enters  into  combination  with  one  or  more 
proportions  of  water,  forming  cellulose  hydrates  of  varying 
complexity.    This  change  is  usually  termed  hydrolysis. 

With  mineral  acids  like  sulphuric  and  hydrochloric  acids, 
cellulose,  if  boiled  in  weak  solutions,  is  converted  into  a 
non-fibrous  brittle  substance  having  the  composition 

C12  H20  Oio  2  H2  0 
to  which  the  name  hydra-cellulose  has  been  given.  Similar 
changes  occur,  but  at  a  much  slower  rate,  when  cellulose  is 


28 


THE  MANUPACTTJBE  OF  PAPER 


in  contact  with  free  acids  at  ordinary  temperatures.  For  this 
reason  it  is  important  that  paper,  when  finished,  should  not 
be  contaminated  with  free  acid. 

The  nature  and  extent  of  the  chemical  change  can  be 
varied  by  altering  the  strength  of  the  acid  and  the  con- 
ditions of  treatment.  The  manufacture  of  parchment  paper 
is  an  example  of  the  practical  utility  of  the  chemical  reaction 
between  cellulose  and  acid.  A  sheet  of  paper  is  dipped  into 
a  mixture  of  three  parts  of  strong  sulphuric  acid  and  one 
part  of  water,  when  it  becomes  transparent.  Left  in  the 
solution  it  dissolves,  but  if  taken  out  and  dipped  into  water 
in  order  to  wash  off  the  acid  the  reaction  is  stopped,  and  a 
tough  semi-transparent  piece  of  parchment  is  obtained.  The 
cellulose  is  more  or  less  hydrated,  having  the  composition 

Cl2  H20  Oio  H2  0, 
a  substance  having  the  name  amyloid. 

Oxidation. — Cellulose  is  only  oxidised  to  any  appreciable 
extent  by  acid  and  alkali' if  treated  under  severe  condi- 
tions. It  is  remarkable  that  the  processes  necessary  for 
isolating  paper  pulp  from  plants  when  digested  with  these 
chemical  reagents  do  not  act  upon  or  destroy  the  fibre,  and 
this  capacity  for  resisting  oxidation  has  rendered  cellu- 
lose extremely  valuable  to  many  of  the  most  important 
industries. 

The  resistant  power  of  the  cellulose  is,  however, 
broken  down  by  the  use  of  acid  and  alkali  in  concentrated 
form. 

Oxalic  and  acetic  acids  are  obtained  when  cellulose  is 
heated  strongly  at  250°  C.  with  solid  caustic  soda. 

Oxy-cellulose,  a  white  friable  powder,  is  produced  by  means 
of  strong  mineral  acids.  Nitric  acid  at  100°  C.  attacks  the 
fibre  very  readily  and  produces  about  30 — 40  per  cent,  of 
the  oxidised  cellulose. 


CELLULOSE  AND  PAPER-MAKING  FIBRES 


29 


Cellulose  Derivatives. 

The  great  number  of  compounds  and  derivatives,  i.e., 
substances  obtained  by  chemical  treatment,  may  be  judged 
from  the  following  list.  The  substances  of  commercial 
importance  are  suitably  distinguished  from  those  of  merely 
scientific  interest  by  the  printing  of  the  names  in  small 
capitals. 

Acetic  Acid. — An  important  commercial  product  obtained 
by  the  destructive  distillation  of  wood.  The  crude 
pyroligneous  acid  is  first  neutralised  with  chalk  or 
lime,  and  the  calcium  acetate  formed  then  distilled 
with  sulphuric  acid.  Wood  yields  5  to  10  per  cent, 
of  its  weight  of  acetic  acid  according  to  the  nature 
of  the  wood. 

Acetone. — A  solvent  for  resins,  gums,  camphor,  gun  cotton, 
and  other  cellulose  products.  Prepared  by  distilling 
barium  or  calcium  acetate  in  iron  stills,  the  acetate 
being  obtained  from  the  crude  acetic  acid  produced  by 
the  dry  distillation  of  wood. 

Acid  Cellulose.— (^QQ  Hydral-Cellulose.) 

Adipo- Cellulose. — A  distinct  compound  cellulose  present  in 
the  complex  cuticular  tissue  of  plants,  and  separated 
easily  by  suitable  solvents  from  the  wax  and  oily 
constituents  also  present. 

Alkali  Cellulose. — When  cotton  pulp  is  intimately  mixed 
with  strong  caustic  soda  solution,  this  compound  is 
formed.    It  is  utilised  in  the  manufacttu-e  of  Viscose. 

Amyloid. — Strong  sulphuric  acid  acts  upon  cellulose  and 
converts  it  into  a  gelatinous  semi-transparent  substance 
to  which  the  name  amyloid  has  been  given.  (See 
Parchment  Paper.) 


30  THE  MANUFACTUEE  OF  PAPER 

Ballistite. — A  smokeless  powder  composed  of  nearly  equal 
parts  of  nitro-glycerine  and  nitrated  cellulose,  with  a 
small  quantity  of  diphenylamine. 

Carbohydrate. — A  large  number  of  important  commercial 
products,  such  as  cellulose,  sugars,  starches,  and  gums, 
consist  of  the  elements  carbon,  hydrogen,  and  oxygen, 
associated  in  varying  proportions.  The  ratio  of 
hydrogen  to  oxygen  in  these  compounds  is  always  2 : 1 
(Ha  and  0). 

Cellulose  CqHwO^. 
Sugar  CeHiaOe. 
Dextrin  n  (Ce  Hio  O5). 

To  all  these  substances  the  term  carbohydrate  is 
applied. 

Celloxin  (Tollens). — A  substance  having  the  stated  com- 
position CgHeOe  considered  to  be  present  in  oxidised 
derivatives  of  cellulose. 

Celluloid. — This  well-known  material  is  made  by  incor- 
porating camphor  with  nitro-cellulose,  a  plastic  ivory- 
like substance  being  ]3roduced.  In  practice  the  process 
is  as  follows : — Wood  pulp  or  wood  pulp  paper  is 
saturated 'with  a  mixture  of  sulphuric  acid  (five  parts) 
and  nitric  acid  (two  parts),  which  produces  nitrated 
cellulose.  The  product  is  washed,  ground,  and  mixed 
with  camphor,  the  mastication  being  effected  by  heavy 
iron  rollers.  The  mass  thickens  and  can  be  removed 
in  the  form  of  thick  sheets.  These  sheets  are  submitted 
to  great  pressure  between  steam-heated  plates.  The 
cake  obtained  is  cut  into  sheets  of  any  desired  thick- 
ness, seasoned  by  prolonged  storage,  and  afterwards 
worked  up  into  boxes,  combs,  brush-backs,  and  many 
other  domestic  articles  of  a  useful  and  ornamental 
character. 


CELLULOSE  AND  PAPEE-MAKING  FIBEES  31 

Cellulose  Acetate  (Cross). — If  cellulose  is  heated  with 
acetic  anhydride  at  180°  C,  viscous  solutions  of  the 
acetates  are  obtained.  The  process  yielding  a  definite 
acetate  of  commercial  value  is  based  upon  the  following 
reaction : — 100  parts  of  cellulose  prepared  from  the 
sulpho-carbonate  are  mixed  with  120  parts  of  zinc 
acetate,  heated  and  dried  at  105°  C.  Acetic  anhydride 
is  added  in  small  quantity,  and  100  parts  of  acetyl 
chloride.  At  a  temperature  of  50°  C.  the  mixture 
becomes  liquid,  and  cellulose  acetate  is  subsequently 
obtained  as  a  white  powder. 

The  compound  can  be  used  in  the  place  of  cellulose 
nitrate,  and,  being  non-explosive,  may  gradually  replace 
the  latter  in  many  industrial  applications. 

Cellulose-Benzoate. — When  alkali  cellulose  is  heated  with 
benzoyl  chloride  and  excess  of  caustic  soda,  this 
substance  is  obtained. 

Cellulose  Hydrate. —  The  substances  produced  by  the  action 
of  acid  and  alkali  on  cellulose  under  certain  strictly 
defined  conditions  are  bodies  containing  cellulose 
united  with  water  to  form  hydrates.  The  industrial 
applications  of  cellulose  based  upon  this  reaction  are 
described  under  the  special  headings. 

Cellulose  Nitrate.  — A  considerable  number  of  derivatives 
are  obtained  by  bringing  cellulose  into  contact  with  nitric 
acid.  Variations  in  the  strength  of  the  acid,  the  tempera- 
ture of  reaction,  and  the  time  of  contact  determine  the 
nature  of  the  product.  The  best  known  nitrates  are  : — 
Cellulose  di-nitrate. 

Cellulose  tri-nitrate  and  tetra-nitrate,  present  chiefly 

in  pyroxyline. 
Cellulose  penta-nitrate. 

Cellulose  hexa-nitrate,  the  chief  constituent  of  gun- 
cotton. 


32  THE  MANUFACTURE  OF  PAPER 

Charcoal. — Not  a  cellulose  derivative  in  the  strict  sense  of 
the  term,  charcoal  being  a  residue  obtained  in  the  dry 
distillation  of  wood. 

Collodion. — A  soluble  nitrate  of  cellulose  used  in  photo- 
graphy.   (See  Pyroxyline.) 

Cordite. — A  smokeless  powder  consisting  mainly  of  nitro- 
glycerine and  gun-cotton  mixed  with  acetone.  The 
materials  are  thoroughly  incorporated  and  the  resultant 
paste  formed  into  threads  which  are  dyed  and  then  cut 
up  into  suitable  lengths  for  cartridges. 

Cuto-Cellulose. — Synonymous  with  adipo-cellulose. 

Dextron. — A  compound  prepared  from  the  waste  liquors  of 
the  bisulphite  process  used  for  the  manufacture  of  wood 
pulp.    Kesembles  dextrin  in  its  physical  properties. 

Dextrose. — A  carbohydrate  which  can  be  obtained  by  the 
action  of  mineral  acids  on  cellulose.  Commercial 
dextrose,  or  glucose,  is  prepared  by  the  conversion  of 
starch  with  sulphuric  acid.  The  starch  is  mixed  with 
dilute  acid  at  a  fixed  temperature,  and  the  starch  milk 
obtained  poured  gradually  into  a  vessel  containing 
dilute  acid,  which  is  maintained  at  boiling  point.  The 
conversion  is  complete  and  rapid. 

Explosives. -^The production  of  the  several  cellulose  nitrates 
has  given  rise  to  a  great  number  of  highly  explosive 
substances. 

Blasting  Gelatine. — A  mixture  of  nitro -glycerine  with 
cellulose  nitrates. 

Amherite,  Ballistite,  Cordite,  and  other  smokeless 
powders,  consisting  of  nitro-glycerine  and  cellulose 
nitrates  in  about  equal  proportions. 

Sporting  poivders  made  by  mixing  nitro-cellulose  with 
barium  nitrate,  camphor  nitro-benzene,  such  as  indnrite, 
plastomenite ,  etc. 
Glucose.  —(See  Dextrose.) 


CELLULOSE  AND  PAPER-MAKING  FIBRES 


33 


Gun-cotton. — An  explosive  prepared  by  the  action  of 
nitric  acid  on  cotton.  Selected  cotton  waste  suitably 
opened  up  is  immersed  in  a  mixture  of  three  parts  of 
nitric  acid  by  weight  (1"50  sp.  gr.)  and  one  part  of 
sulphuric  acid  by  weight  (1'85  sp.  gr.)  and  submitted 
to  a  number  of  processes  by  which  the  nitration  is 
properly  effected  so  as  to  produce  a  nitro-cellulose  of 
uniform  composition.  The  material  is  washed,  reduced 
to  pulp,  and  moulded  into  various  forms. 

Hemi-Cellidose. — The  constituents  of  plant  tissues  are 
extremely  varied  in  character.  Many  plants  contain 
substances  which  resemble  true  cellulose,  but  differing 
from  it  in  being  easily  converted  by  hydrolysis,  and  by 
the  action  of  dilute  acids,  into  carbohydrates.  Plants 
which  contain  a  large  proportion  of  such  constituents 
are  termed  hemi-celluloses.  In  some  cases  certain 
crystallisable  sugars  can  be  obtained  by  hydrolysis 
under  suitable  conditions. 

Hydral-CelluloseiBnmcke). — A  Compound  of  merely  scientific 
interest,  resulting  from  the  treatment  of  cellulose  with 
hydrogen  peroxide.  When  acted  upon  by  alkali  it  is 
decomposed  into  cellulose  and  acid  cellulose,  the  latter 
a  derivative  of  unstable  composition. 

Hydro-Cellulose. — This  product,  a  white,  non-structureless, 
friable  powder,  is  obtained  by  treating  cellulose  with 
hydrochloric  or  sulphuric  acid  of  moderate  strength. 
The  substance  itself  has  no  commercial  value,  but  the 
reaction  is  useful  in  separating  cotton  from  animal 
fabrics.  If  a  woollen  cloth  containing  cotton  is  soaked 
in  dilute  sulphuric  acid,  washed,  and  dried  at  a  gentle 
heat,  the  cotton  is  acted  upon,  and  can  be  beaten  out 
of  the  fabric,  the  wool  resisting  the  acid  treatment. 

Lignin. — The  complex  mixture  of  substances  which  is 
associated  with  cellulose  in  wood,  jute,  and  other 
p.  D 


34  THE  MANUFACTUEE  OF  PAPER 

ligno-celluloses.  The  conversion  of  wood  into  chemical 
pulp  effects  the  removal  of  this  material  more  or  less 
completely.  The  well-known  "  phloroglucine "  test 
for  mechanical  wood  in  papers  is  based  upon  the 
presence  of  lignin  in  the  wood. 

Lig7io- Cellulose. — Wood  and  jute  are  typical  bodies  con- 
sisting of  cellulose  and  complex  non-cellulose,  gene- 
rally described  as  lignin,  associated  together  in  the 
plant  tissue.  The  chemistry  of  the  non-cellulose 
portion  of  wood  is  a  matter  still  under  investigation, 
its  importance  from  a  commercial  point  of  view  being 
obvious  from  the  fact  that  the  removal  of  the  lignin 
during  the  conversion  of  the  wood  into  wood-cellulose 
results  in  a  loss  of  50  per  cent,  of  the  weight  of  wood. 

Lustra-Cellulose.— ^ynonymow^  with  and  suggested  as  a 
more  appropriate  name  for  the  material  usually 
described  as  artificial  silk. 

Mercerised  Cotton. — When  cotton  is  immersed  in  strong 
solutions  of  caustic  soda  a  remarkable  change  sets  in. 
The  physical  structure  of  the  fibre  is  entirely  altered 
from  the  long  flattened  tube  having  a  large  central 
canal  to  a  shorter  cylindrical  tube  in  which  the  canal 
almost  disappears.  Hydration  of  the  cellulose  takes 
place,  and  these  changes  are  taken  advantage  of  in  the 
production  of  mercerised  cloth  (so  named  from  the 
discoverer  of  the  reaction,  Mercer).  Cotton  goods, 
particularly  those  made  of  long  stapled  cotton,  when 
mercerised,  exhibit  a  beautiful  lustre,  and  some 
magnificent  crepon  effects  are  obtained  by  the  process. 

Methoxyl. — A  constituent  of  the  complex  compound  known 
as  ligno-cellulose,  which  is  present  in  wood  and  similar 
fibres.  The  amount  of  methoxyl  in  lignified  tissue  can 
be  accurately  determined,  and  it  has  been  suggested 
that  the  proportion  of  methoxyl  found  in  a  cheap 


CELLULOSE  AND  PAPER-MAKING  FIBRES 


35 


printing  paper  could  be  used  as  a  measure  of 
mechanical  wood  pulp  present. 
Muco-Cellidose. — This  term  is  applied  to  certain  compound 
celluloses  present  chietly  in  mucilages,  gums,  and  in 
seaweeds  (Algae).  The  natural  substances  are  all  of 
commercial  importance — Iceland  moss,  Carragheen, 
Algin,  etc. 

Naphtha. — One  of  the  "products  of  the  dry  distillation  of 
wood,  usually  described  as  wood-naphtha,  or  wood 
spirit. 

Nitro-Cellulose. — The  treatment  of  cellulose  with  nitric 
acid  gives  a  number  of  nitro-celluloses  according  to  the 
conditions  of  the  process.    (See  Cellulose  Nitrates.) 

Oxalic  Acid. — A  substance  of  great  commercial  importance 
prepared  by  heating  the  sawdust  of  soft  wood,  such  as 
pine,  fir,  and  poplar,  with  strong  solutions  of  mixed 
caustic  soda  and  potash  to  dryness.  The  wood  yields 
after  six  hours  a  greyish  mass  containing  about  20  per 
cent,  of  the  acid,  which  is  separated  out  by  water  and 
then  crystallised. 

It  is  used  for  bleaching,  and  as  a  discharge  in  calico 
printing  and  dyeing. 

Oxy-Cellulose. — A  white  friable  powder  produced  by  treating 
cellulose  with  nitric  acid  at  100°  C.  The  oxidation  of 
cellulose  is  brought  about  by  several  reagents  such  as 
chromic  acid,  hypochlorites  of  lime  and  soda,  chlorine, 
and  permanganates.  The  extent  to  which  cloth  has 
been  damaged  by  overbleaching  may  be  determined  by 
a  simple  test  with  methylene  blue  solution,  which  is 
readily  absorbed  by  oxy-cellulose  present  in  such 
fabrics. 

Parchment. — A  tough  paper  prepared  by  the  action  of 

sulphuric  acid  on  unsized  paper.    (See  page  1B7.) 
Pectins, — (See  Pecto-Cellulose.) 


36  THE  MANUFACTURE  OF  PAPER 

Pecto-Cellulose. — A  generic  term  applied  to  many  important 
fibrous  materials,  such  as  flax,  straw,  esparto,  bamboo, 
phormium,  ramie,  &c.,  which  on  alkaline  treatment 
yield  cellulose  for  paper-making,  and  a  non-fibrous 
soluble  residue  of  complex  composition.  These  soluble 
derivatives  are  known  as  pectin  (C32  H48  O32),  pectic 
acid  (C32  H44  O30),  and  metapectic  acid  (C32  H28  O36). 
Although  the  soluble  constituents  of  the  pecto-celhi- 
loses  amount  to  50  per  cent,  by  weight  in  most  cases, 
no  process  for  the  recovery  of  the  product  in  a 
commercial  form  has  yet  been  devised.  (See  descrip- 
tion of  Soda  recovery,  page  78.) 

Pyroxyline. — A  substance  prepared  by  nitrating  cotton. 
The  cotton  is  immersed  in  a  mixture  of  nitric  and 
sulphuric  acids  of  carefully  regulated  strength,  and 
subsequently  washed  free  of  the  acid.  Three  volumes 
of  nitric  acid  (sp.  gr.  1*429)  are  diluted  with  two 
volumes  of  water  and  nine  volumes  of  strong  sulphuric 
acid  (sp.  gr.  1*839)  added.  To  the  solution  when  cool 
the  cotton  is  added  in  small  quantities  at  a  time.  The 
resultant  pyroxyline  is  soluble  in  a  mixture  of  equal 
quantities  of  alcohol  and  ether,  and  in  the  soluble  form 
is  utilised  as  collodion  for  photography. 

Silk,  Artificial. — A  remarkable  substance  made  from 
wood  or  cotton  cellulose,  closely  resembling  silk  in 
appearance  and  physical  properties. 

Nitrated  cellulose  is  dissolved  in  a  mixture  of  equal 
parts  of  alcohol  and  ether. 

The  solution  is  forced  through  five  capillary  tubes 
under  high  pressure,  and  the  filament  so  obtained 
solidifying  at  once  is  wound  together  with  other 
similar  filaments  upon  suitable  bobbins.  Various 
modifications  of  this  general  process  are  in  use,  such 
as  the  solidification  of  the  solution  into  threads  by 


CELLULOSE  AND  PAPER-MAKING  FIBRES  37 


passing  it  into  water ;  the  application  of  solvents  less 
inflammable  than  ether  and  alcohol ;  the  use  of  other 
forms  of  dissolved  cellulose  such  as  those  prepared  by 
means  of  zinc  chloride,  ammoniacal  copper  oxide,  or 
acetic  anhydride.  In  all  cases  the  yarn  or  thread 
is  submitted  to  further  chemical  treatment  for  the 
removal  of  nitric  acid  and  to  render  the  material  non- 
explosive  and  less  inflammable.  The  finished  product 
is  soft  and  supple,  can  be  easily  bleached  and  dyed,  and 
is  capable  of  acquiring  a  high  lustre. 

Smokeless  Powders. — (See  Explosives.) 

Sulpho-Carhonate. — (See  Viscose.) 

Sulphate  Cellulose. — Chemical  wood  pulp  prepared  by 
the  sulphate  process.    (See  page  107.) 

Sulphite  Cellulose. — Chemical  wood  pulp  prepared  by 
the  sulphite  process.    (See  page  107.) 

Viscose. — A  soluble  sulpho- carbonate  of  cellulose,  prepared 
by  treating  cehalose  with  a  15  per  cent,  solution  of 
caustic  soda,  and  shaking  the  product  with  carbon 
bisulphide  in  a  closed  vessel.  The  mixture  forms  a 
yellowish  mass  soluble  in  water,  giving  a  viscous 
solution  which  has  some  remarkable  and  valuable 
properties. 

This  viscose,  on  standing,  coagulates  to  a  hard  mass 
which  can  be  turned  and  pohshed. 

If  s[)read  on  glass  and  coagulated  by  heat,  films  are 
obtained  from  which  the  alkaline  by-products  can  be 
washed  out.  These  films  are  transparent,  colourless, 
very  tough  and  hard. 

Vulcanised  Fibre.  —  Fibre  or  pulp  treated  with  zinc 
chloride  in  acid  solution,  or  otherwise,  for  the 
manufacture  of  hard  boards.    (See  page  139.) 

VViLLESDEN  Goods.— Paper,  fibre,  and  textiles  when  treated 


38 


THE  MANUFACTUEE  OF  PAPER 


with  cuprammonium  oxide  are  partially  gelatinised  on 
the  surface  and  rendered  waterproof.     (See  page  139.) 

Wood  Spirit. — (See  Naphtha.) 

Xylonite, — (See  Celluloid.) 

Fibres  for  Paper-making. 

Although  the  vegetable  world  has  been  explored  from 
time  to  time  for  new  supplies  of  cellulose,  and  some  plants 
have  been  found  serviceable  in  certain  directions,  yet  the 
number  of  fibres  in  actual  use  is  very  limited. 

The  following  table  indicates  the  principal  sources  of  the 
material  required  for  paper-making  : — 


Fibre. 

Linen 

Cotton 

Esparto 
Straw 

Wood 


Flax 

Hemp 

Jute 
Bamboo 

Ramie 

Bagasse 

Manila 
Hemp 


Source  of  tlie  Fibre, 


Hags,  textile  waste. 
Rags,  textile  waste. 

Natural  grass. 

Straw  from  various 
cereals — wheat,  bar- 
ley, oats,  etc. 

Mechanically  ground 
wood. 

Chemically  prepared 
wood. 

Threads,     waste  from 

spinning  mills. 
Spinning     refuse,  old 

rope,  sailcloth,  etc. 
Waste,  old  gunny  bags. 
Natural  stems. 


Bast  fibres  of  the  plant  : 

textile  refuse. 
Sugar-cane  refuse. 

Textile  and  rope  refuse. 


Application  of  the  Fibre. 


High  class  writings  and  print- 

High  class  writings  and  print- 
ings. 

Writings  and  printings. 
Printings,  box  and  card  boards. 


Cheap  papers,  boxboards, 
middles,  tickets  and  cards, 
writings  and  printings. 

Writings  and  printings. 

Wrappings,  boards,  cable 
papers. 

Wrappings,  boards,  cable 
papers,  strong  writings. 

Wrappings,  boxboard,  cards. 

Writings  and  printings  (not  in 
Europe,  and  only  limited 
quantities  elsewhere). 

Rarely  used,  except  in  special 
cases. 

Common  papers  (chiefly  ex- 
perimental results). 
Wrappings,  cable  papers. 


CELLULOSE  AND  PAPER-MAKING  EIBRES  39 


ExjMting  New  Fibres. — The  exploitation  of  any  new 
paper-making  fibre  requires  attention  to  certain  important 
details,  which  may  be  fairly  considered  in  the  following 
order : — 

(1)  Supply. — The  supply  of  material  must  be  plentiful 
and  obtainable  in  large  quantities.  Too  often  this  question 
is  entirely  neglected  by  those  who  bring  new  fibres  to  the 
notice  of  paper-makers,  probably  because  they  do  not 
realise  that  enormous  quantities  of  material  are  necessary 
to  supply  even  a  very  small  section  of  the  paper  trade,  the 
fact  being  that  few  plants  yield  more  than  half  their  weight 
of  paper-making  fibre. 

(2)  Suitability. — The  fibre  should  be  properly  examined 
as  to  its  chemical  and  physical  properties  in  a  laboratory 
equipped  with  appliances  for  its  conversion  into  bleached 
paper  pulp  on  a  small  scale.  The  examination  of  the  fibre 
would  include  tests  as  to  the  amount  of  pulp  which  can  be 
obtained  from  one  ton  of  raw  material,  the  approximate 
cost  of  treatment,  and  details  as  to  the  value  of  the  fibre  for 
paper-making. 

(3)  Cost  of  Raiv  Material. — If  the  supply  of  material 
seems  to  be  sufiicient,  and  the  paper  pulp  obtained  possesses 
suitable  qualities,  then  it  is  necessary  to  get  accurate  infor- 
mation as  to  the  cost  of  the  fibre  delivered  to  some  given 
spot  at  or  near  the  place  of  collection. 

The  exploitation  of  any  new  fibre  for  paper-making  pur- 
poses will  involve  a  recognition  of  the  fact  that  the  raw 
material  must  be  converted  into  pulp  at  or  near  the  place 
where  the  material  is  most  abundant. 

The  only  interesting  exception  to  this  is  the  case  of 
esparto  fibre,  which  is  imported  into  England  in  large 
amount,  but  this  is  only  possible  because  esparto  possesses 
most  valuable  paper-making  qualities,  and  is  obtained  in 
countries  close  to  England,  where  large  quantities  are 


40 


THE  MANUFACTURE  OF  PAPER 


consumed.  It  is  doubtful  whether  other  fibres  could  be 
utilised  in  the  same  way. 

(4)  The  Cost  of  Manufacture  at  or  near  the  place  of 
collection  requires  to  be  carefully  worked  out,  due  con- 
sideration being  given  to  the  actual  cost  of  chemicals  on  the 
spot,  cost  of  labour,  and  the  conditions  under  which  the 
maintenance  of  machinery  can  be  efficiently  looked  after. 

(5)  Carriage  and  Freight  Charges  are  the  last,  but  by  no 
means  the  least,  items  of  importance.  It  is  not  too  much  to 
say  that  the  whole  success  of  the  exploitation  of  new  paper- 
making  fibre  hangs  entirely  upon  this  item,  the  majority  of 
many  fibres  which  have  been  brought  to  the  notice  of  the 
trade  being  suitable,  but  impracticable,  solely  on  account 
of  these  and  similar  commercial  considerations. 

In  the  pages  of  the  trade  press  for  the  last  few  years  the 
following  fibres  have  been  noticed  : — 

(1)  Flax  Pulp. — This  material  was  to  be  obtained  from 
flax  straw.  Attempts  were  made  on  a  commercial  scale  to 
produce  quantities  of  flax  fibre,  but  so  far  the  efforts  made 
have  not  been  very  successful. 

(2)  Ramie  Fibre. — This  material  has  been  exploited  over 
and  over  again,  chiefly  for  textile  trades,  its  application  as  a 
paper-making 'material  being  limited  to  small  quantities 
used  for  special  purposes  such  as  bank  notes.  The  fibre  is 
too  valuable,  except  for  textile  industries,  and  can  only 
come  into  the  paper  trade  as  a  waste  material  from  such 
sources. 

(3)  Tobacco  Fibre  has  been  before  the  trade  for  some 
years,  the  idea  being  to  utilise  tobacco  stems  and  other 
tobacco  waste  for  the  manufacture  of  paper  suitable  for  use 
as  wrappers  for  cigars,  cigarettes,  and  similar  purposes. 

(4)  Agave  Fibre. — This  name  is  given  to  a  large  and 
important  genus  of  fibre-yielding  plants  found  chiefly  in 
Central  America.    It  is  also  found  in  India,  and  in  1878  an 


CELLULOSE  AND  PAPER-MAKING  FIBEES 


41 


experiment  was  made  for  the  manufacture  of  paper  at  a 
mill  near  Bombay,  but  this  did  not  give  any  satisfactory 
results,  probably  on  account  of  the  primitive  methods  used 
in  treatment. 

(5)  Bagasse. — The  waste  material  from  sugar-cane  has 
been  looked  upon  for  many  years  as  a  desirable  fibre,  much 
time  and  labour  having  been  given  to  the  utilisation  of  this 
material.  In  spite  of  these  efforts  bagasse  still  remains  an 
almost  useless  and  unworkable  material.  This  is  partly 
due  to  inferiority  of  the  pulp  and  partly  due  to  difficulties 
connected  with  its  treatment'.  Probably  cultivation  of  the 
plant  for  the  sake  of  its  fibre  instead  of  the  sugar  might 
give  better  results. 

(6)  Peat. — The  attempts  made  to  utilise  peat  for  paper- 
making  are  probably  fresh  in  the  minds  of  those  paper- 
makers  interested  in  the  production  of  wrappers  and 
boxboards.  The  nature  of  peat,  however,  is  such  as  to 
exclude  the  hope  of  making  any  useful  article.  The  material 
has  been  exploited  by  companies  in  Austria,  Ireland,  and 
Canada  on  a  fairly  large  scale,  with  but  a  limited  amount 
of  success. 

(7)  Cottonseed  Hulls. — Many  patents  have  been  taken 
out  for  the  chemical  treatment  of  cotton-seed  waste  and 
having  for  their  object  the  removal  of  the  particles  of  seed 
hulls,  so  as  to  obtain  a  pure  cotton  pulp.  The  scheme 
sounds  attractive,  but  there  are  so  many  conditions  which 
have  to  be  taken  account  of  that  the  commercial  success  of 
any  undertaking  based  on  the  use  of  cotton- seed  hulls  is 
very  questionable.  The  fact  is  that  the  hulls  have  a 
market  value  quite  apart  from  the  possibility  of  their 
application  to  paper-making,  and  this  initial  cost  would 
prevent  paper-makers  from  buying  the  material  owing  to 
the  large  quantity  necessary  for  the  manufacture  of  one  ton 
of  pure  pulp. 


42 


THE  MANUFACTUEE  OE  PAPEE 


(8)  Ajjocynum. — This  plant  is  said  to  be  utilised  to  some 
extent  by  the  Kussian  Government  in  the  manufacture  of 
bank  notes,  the  plant  being  cultivated  at  Poltava.  This 
is  an  instance  of  the  particular  application  of  a  fibrous 
material  in  limited  quantities,  a  proposition  which  is 
always  feasible  in  the  case  of  special  requirements. 

(9)  Cornstalk. — This  fibre  has  been  chiefly  exploited  in 
America,  experts  having  been  attracted  by  the  enormous 
quantities  of  cornstalk  available  in  the  several  wheat- 
producing  States.  The  manufacture  of  paper  pulp  from 
this  material  on  a  large  scale  has  yet  to  be  established. 

(10)  Japanese  Paper  Fibres. — In  Eastern  countries  a 
great  number  of  fibrous  plants  are  utilised  in  small  quanti- 
ties for  the  manufacture  of  special  papers.  It  is  obvious 
that  in  these  Eastern  countries  the  employment  of  fibres 
which  are  not  cultivated  in  large  bulk  is  readily  possible 
when  the  question  of  price  obtained  for  the  paper  and  the 
cost  of  production  are  considered.  Of  such  fibres  may  be 
mentioned  the  Mitsumata  and  Koclzu,  easy  of  cultivation  and 
giving  a  good  yield  of  material  per  acre  of  ground.  The 
waxed  papers  used  for  stencils  in  duplicating  work  on  the 
typewriter  are  made  from  these  fibres.  The  paper  Mul- 
berry is  also  'a  well-known  fibre ;  while  a  third  species 
particularly  valuable  for  thin  papers  is  the  Gampi. 

(11)  Antaimoto  Fibre. — The  bark  of  this  shrub  is  utilised 
in  Madagascar  in  very  small  quantities  for  local  purposes 
and  possesses  little  interest  for  paper-makers. 

(12)  Refuse  Hempstalk. — The  suggestion  of  the  use  of 
this  material  comes  from  Italy,  the  hempstalk  having  been 
experimented  with  at  San  Cesario  Mill.  This  also  is  a  fibre 
of  a  local  interest  only.  The  percentage  of  cellulose  is  very 
high,  being  over  50  per  cent. 

(13)  Papyrus. — The  revival  of  this  celebrated  material  is 
of  comparatively  recent  date.    It  should  be  noted  that  the 


CELLULOSE  AND  PAPER-MAKING  FIBRES  43 


manufacture  of  papyrus  as  carried  out  by  the  Egyptians,  by 
smoothing  out  layers  of  bark  in  order  to  utilise  them  as 
sheets  of  paper,  and  the  present  day  proposals  which  involve 
the  production  of  paper  pulp  from  papyrus,  are  two  entirely 
different  propositions,  and  the  success  of  the  old  Egyptian 
method  cannot  be  referred  to  as  any  assurance  of  success 
for  the  production  of  paper  from  papyrus  along  modern 
lines.  The  exploitation  of  this  fibre  must  follow  the 
lines  of  modern  research  and  commercial  investigation, 
and  its  value,  if  any,  could  then  be  established. 

(14)  Pousolsia. — This  is  a  fibre  of  the  same  family  as 
hemp  and  ramie.  The  value  of  this  material  is  at  present 
unknown,  but  the  ultimate  fibre  appears  to  possess  a  most 
extraordinary  length.  Very  little  information  is  available 
at  present  as  to  its  value  for  paper-making. 

(15)  Bamboo. — This  material  has  been  before  the  paper 
trade  for  many  years,  having  first  been  exploited  seriously 
by  Mr.  Thomas  Koutledge  in  1875.  Since  that  date  a  good 
deal  of  work  has  been  done  in  connection  with  the  fibre,  but 
not  until  recently  has  the  investigation  been  made  of  a 
sufficiently  extensive  character  to  enable  paper-makers  to 
form  some  conclusions  as  to  the  best  methods  of  obtaining 
a  reliable  paper  pulp.  The  researches  of  the  writer  in  India 
go  to  prove  that  with  any  fibre  it  is  necessary  to  take  into 
account  all  the  factors  likely  to  affect  the  final  cost  of  the 
paper  pulp  delivered  to  any  given  paper  mill. 

The  figures  given  in  a  report  recently  published,  "  The 
Manufacture  of  Paper  and  Paper  Pulp  in  Burma,"  show  the 
necessity  of  thorough  investigation  into  all  the  points  likely 
to  affect  the  final  results,  viz.,  the  price  at  which  the  paper 
pulp  can  be  sold  in  England,  assuming  that  the  fibre  in 
question  is  suitable  for  the  manufacture  of  paper. 

Examination  of  Fibres. — The  exact  chemical  analysis  of 


44 


THE  MANUFAOTUEE  OE  PAPER 


a  new  fibre  is  necessary  in  order  to  establish  completely 
its  value  for  textile  and  paper-making  purposes,  but  the 
investigation  of  the  suitability  of  the  fibre  for  paper-making 
may  be  simplified  by  simple  reduction  of  the  raw  material 
with  caustic  soda.  The  following  process  is  sufficient  for  all 
practical  purposes : — 

Condition  of  Sample. — A  record  should  be  made  of  the 
general  appearance  of  the  sample,  its  condition  and  the 
amount  available  for  the  investigation.  Any  information 
available  as  to  the  source  of  supply  and  the  growth  of  the 
plant  should  also  be  noted. 

Preparation  of  Sample. — The  material  is  cut  up  into 
small  pieces.  The  most  convenient  appliance  for  this  pur- 
pose is  a  mitre  cutter  as  used  by  picture-frame  makers.  If 
the  sample  is  a  piece  of  wood,  sections  one  inch  thick  cut 
across  the  grain  of  the  wood  are  most  suitable,  as  they  can 
be  readily  cut  up  into  thin  flakes  by  this  machine. 

Moisture  in  Sample. — A  small  average  sample  should 
be  dried  at  100°  C.  for  the  determination  of  moisture. 

Treatment  ivith  Caustic  Soda. — About  two  hundred  grams 
of  the  raw  material  is  closely  packed  into  a  small  digester 
or  autoclave  and  covered  with  a  solution  of  caustic  soda 
having  a  specific  gravity  of  1*050.  A  perforated  lead  disc 
should  be  placed  above  the  sample  in  the  digester  to  prevent 
any  of  it  from  floating  above  the  level  of  the  solution.  The 
material  should  be  digested  for  five  or  six  hours  at  a 
pressure  of  50  lbs.  The  conditions  of  treatment  here  given 
will  need  to  be  varied  according  to  the  nature  of  the  fibre. 
Some  materials  can  be  readily  converted  into  pulp  with 
weaker  liquor  and  at  a  lower  pressure,  while  others  will 
require  prolonged  treatment.  These  conditions  must  be 
varied  according  to  judgment  or  according  to  the  efl'ects 
produced  by  the  conditions  already  set  out. 

Unhleached  Pulp.  —  The  contents  of  the  digester  are 


CELLULOSE  AND  PAPEK-MAKING  FIBEES  45 


emptied  out  into  an  ordinary  circular  sieve  provided  with 
a  fine  copper  wire  bottom,  having  a  mesh  of  about  sixteen 
to  the  inch.  The  sieve  is  immersed  in  water  and  the  con- 
tents partially  washed  with  hot  water.  The  partially  washed 
material  is  squeezed  out  by  hand  and  tied  up  in  a  strong 
cloth  and  then  kneaded  thoroughly  by  hand  in  a  basin 
of  water  which  is  repeatedly  renewed  until  the  fibre  is 
thoroughly  washed.  The  process  of  kneading  at  the  same 
time  reduces  the  fibre  to  the  condition  of  pulp.  The  water  is 
carefully  squeezed  out  of  the  pulp  by  hand,  and  the  moist 
pulp  is  then  divided  into  two  equal  parts,  the  first  of  which 
is  made  up  into  sheets  of  any  convenient  size,  care  being 
taken  that  none  of  the  fibre  is  lost.  These  sheets  are  then 
dried  in  the  air  and  preserved  as  samples  of  unbleached 
pulp,  a  record  being  made  of  the  weight  produced. 

Bleached  Pulp. — The  second  portion  of  the  moist  pulp  is 
mixed  with  a  solution  of  bleach,  the  strength  of  which  has 
been  accurately  determined  by  the  usual  methods.  The 
amount  of  bleach  added  should  be  about  20  j)er  cent,  of  the 
weight  of  air-dry  fibre  present  in  the  moist  sample  of  pulp. 
The  pulp  should  be  bleached  at  a  temperature  not  exceeding 
38°  C,  and  when  the  colour  has  reached  a  maximum  the 
amount  of  bleach  remaining  in  solution  is  ascertained  by 
titration  with  standard  arsenic  solution.  In  this  way  the 
amount  of  bleaching  powder  required  to  bleach  the  pulp  is 
determined.  The  product  is  then  made  up  into  sheets  of 
pulp  which  are  dried  by  exposure  to  air  and  subsequently 
weighed. 

Yield  of  Pidp. — ^The  percentage  yield  of  finished  pulp 
obtained  from  the  raw  material  is  determined  from  the 
figures  arrived  at  in  the  experiment  described,  and  the 
weight  of  raw  material  necessary  to  produce  one  ton  of 
bleached  pulp  is  readily  calculated. 

Examination  of  Bleached  Fibre, — The  fibre  should  be 


46 


THE  MANUFACTUEE  OF  PAPER 


carefully  examined  under  the  microscope  and  a  record 
made  of  general  microscopic  features,  especially  with  refer- 
ence to  the  length  and  diameter  of  the  fibres,  and  the 
proportion  of  cellular  matter  present,  if  any. 

Samjde  of  Paper. — It  is  only  in  the  case  of  short-fibred 
material  similar  to  esparto  and  straw  that  sheets  of  paper 
capable  of  giving  comparative  results  as  to  strength  can  be 
made.  The  figures  obtained  with  fibrous  materials  of  this 
kind  are  only  comparative,  because  it  is  possible  in  practice 
to  make  a  much  stronger  sheet  of  paper  when  the  material 
is  beaten  properly  under  normal  conditions. 

A  similar  investigation  should  be  made  by  submitting  the 
fibre  to  treatment  with  bisulphite  of  lime,  that  is  to  say,  if 
the  fibre  lends  itself  to  such  a  process.  A  lead-lined  digester 
is  necessary,  and  the  solution  employed  is  bisulphite  of  lime 
prepared  according  to  the  directions  given  on  page  160. 

The  preparation  of  sulphite  pulp  requires  more  attention 
than  the  manufacture  of  soda  pulp.  It  is  most  important  that 
the  digester  should  be  absolutely  tight  in  order  to  prevent 
the  escape  of  any  free  sulphurous  acid  gas,  and  the  contents 
of  the  digester  must  be  heated  slowly  until  the  maximum 
pressure  has  been  reached. 


CHAPTER  III 

THE  MANUFACTURE  OF  PAPER  FROM  RAGS 

The  word  rag  is  used  to  designate  a  very  wide  range  of 
raw  material  suitable  for  conversion  into  paper.    In  the 


Pig.  6. — A  Eag  Sorting  House. 


case  of  high-class  hand-made  writing  papers  only  the  best 
qualities  are  employed,  such  as  new  linen  and  cotton 


48 


THE  MANUFACTUEE  OF  PAPEE 


cuttings  from  factories,  or  well-sorted  rags  of  domestic 
origin.  The  usual  classification  adopted  by  merchants 
who  supply  the  paper  mills  is  somewhat  as  follows  : — 

New  white  linen  cuttings  (from  textile  factories). 

New  white  cotton  cuttings  (from  textile  factories). 

Fine  whites  (domestic  rags). 

Outshots  (a  quality  between  fines  and  seconds). 

Seconds  (a  grade  inferior  to  fines). 

Thirds  (inferior  and  dirty  well-worn  rags). 

Coloured  prints  (of  all  grades  and  colours). 

Fustians  and  canvas. 

Manila  and  hemp  rope. 

Baggy,  gunny,  and  jute. 
The  total  amount  of  rag  used  in  England  for  paper- 
making  is  not  known.  The  only  figures  available  refer 
to  rags  imported;  and  these  cannot  be  regarded  as  a  measure 
of  consumption,  which  could  only  be  arrived  at  by  first 
ascertaining  the  quantity  of  home  rags  used.  The  imports 
of  rag  at  stated  periods  are  given  in  the  appended  table  : — 


Eags  Imported  into  England. 


1872. 

1882. 

1892. 

1902. 

1905. 

Weight  (tons)  . 

22,254 

21,200 

23,032 

18,692 

23,681 

Value 

£373,035 

£303,349 

£214,065 

£173,732 

£224,232 

Sorting  and  Cutting. — All  rags  on  arrival  at  the  mill  are 
carefully  sorted.  This  process  is  conducted  entirely  by 
women,  who  sort  and  cut  up  the  rags  at  special  tables 
provided  with  cutting  knives  curved  in  shape  similar  to  a 
scythe.  These  are  fixed  at  an  angle  in  the  centre  of  the 
table,  with  the  back  towards  and  in  front  of  each  work- 
woman.   The  top  of  the  table  is  made  of  thick  coarse  wire 


THE  MANUFACTUEE  OF  PAPER  FR(3M  RAGS  49 


so  that  some  of  the  dirt  and  foreign  impurities  may  fall 
through.  All  buttons,  hooks  and  eyes,  pins,  leather,  pieces 
of  rubber,  and  other  articles  are  carefully  removed,  while 
seams  and  hems  are  also  opened  out.  The  rags  are  cut  into 
slips  3 — 5  inches  long  and  then  recut  crosswise,  and  thrown 
into  suitable  baskets  or  receptacles  standing  round  the 


Fig.  7. — A  Rag  Duster. 

table,  by  which  means  the  sorting  operation  is  effectually 
carried  out.  '  The  care  and  attention  given  to  the  sorting  is 
an  important  item  in  the  manufacture  of  papers  of  uniform 
quality,  and  in  the  best  mills  the  sorting  is  carried  out 
to  such  an  extent  that  twenty  or  twenty-five  grades  are 
obtained. 

Dusting. — The  rags  are  next  passed  through  a  machine 
which  removes  dirt.    This  i^  a  hollow  cylindrical  or  conical 
p.  E 


50 


THE  MANUFACTURE  OF  PAPER 


drum  having  an  external  covering  of  coarse  wire  cloth, 
which  rotates  inside  a  wooden  box.  The  shaft  is  provided 
with  projecting  spikes,  so   that  the  rags  are  violently 


Fig.  8.— a  Rag  Cutter. 


agitated  in  their  passage  through  the  machine.  The  dirt 
and  other  impurities  fall  through  the  wire  on  to  the  floor 
of  the  room,  while  the  clean  rags  are  discharged  from  the 
lower  end  of  the  drum.  The  loss  in  weight  varies  according 
to  the  condition  of  the  rags.    With  good  materials  the  loss 


THE  MANUFACTURE  OF  PAPER  FROM  RAGS 


51 


may  only  be  1 — 2  per  cent.,  while  with  dirty  common 
rags  the  loss  during  cleaning  and  dusting  may  amount  to 
10  per  cent. 

Boiling. — The  further  purification  of  the  rags  is  effected 
by  a  chemical  treatment,  viz.,  boiling  at  a  high  temperature 


Fig.  9. — Interior  of  Paper  Mill  for  Hand-made  Paper 
(R.  Batchelor  &  Sons). 

with  alkaline  substances,  which  process  removes  fatty, 
glutinous,  and  starchy  matter  from  the  material. 

For  this  purpose  a  spherical  digester  is  used,  generally 
7 — 9  feet  diameter,  and  capable  of  holding  2 — 2 J  tons  of 
rag.  The  boiler  or  digester  is  filled  with  dusted  rags,  and 
the  requisite  amount  of  alkaline  solution  added.  The  man- 
hole is  then  closed,  and  steam  admitted  through  the  hollow 

E  2 


52 


THE  MANUFACTUEE  OF  PAPER 


trunnions  until  the  pressure  reaches  20  or  30  lbs.,  at  which 
pressure  the  boiling  is  continued  for  three  to  six  hours 
according  to  requirements,  the  digester  rotating  slowly  the 


p  /  2  J  Meter 

I'I'I    I    I   I   1    I   '  '  '   J 

]?jG.  10. — View  of  a  Eag  Boiler,  showing  connections. 

whole  time  in  order  that  the  rags  may  be  evenly  and 
thoroughly  boiled. 

The  liquor  employed  for  boiling  is  a  solution  of  caustic 
soda,  carbonate  of  soda,  or  milk  of  lime.  In  the  case  of 
caustic  soda  the  amount  required  varies  from  5  to  10  per 
cent,  of  the  weight  of  rag.  Caustic  soda  is  preferable  to 
lime,  because  it  acts  upon  the  grease  and  other  fatty 


THE  MANUFACTUEE  OP  PAPEE  FEOM  BAGS 


53 


matters,  forming  a  soluble  compound  which  is  freely 
removed  in  the  subsequent  process  of  washing.  Many 
paper-makers,  however,  use  milk  of  lime,  carefully  strained 
through  fine  cloth,  almost  exclusively.  Considerable  expe- 
rience and  skill  are  necessary  in  this  operation  in  order 
to  avoid  injury  to  the  fibre  not  only  as  regards  its  strength, 
but  also  its  colour. 

Washing. — When  the  rags  have  been  sufficiently  boiled, 
the  steam  is  turned  off  and  the  pressure  allowed  to  fall. 
This  can  be  effected  quickly  by  blowing  off  from  a  valve 
fixed  at  the  bottom  of  the  boiler  oj^posite  to  the  manhole. 
The  cover  is  removed  from  the  boiler  and  the  boiler  slowdy 
rotated  in  order  that  the  contents  may  be  discharged  into 
a  tank  placed  below.  The black  liquor,"  as  it  is  called, 
is  then  drained  away  from  the  rags,  which  are  immediately 
subjected  to  a  preliminary  washing.  The  process  of  washing 
must  be  carried  out  in  a  thorough  manner  in  order  to 
remove  all  soluble  compounds,  which  if  left  would  cause  an 
unnecessary  waste  of  bleach  in  the  subsequent  stages  of 
purification.  There  are  many  schemes  employed  for 
washing,  most  of  them  being  devised  with  the  idea  of 
using  a  minimum  quantity  of  water. 

The  most  general  practice,  in  the  absence  of  special 
machinery,  is  the  preliminary  treatment  in  the  tank  below 
the  digester,  followed  by  a  more  complete  washing  process 
in  a  machine  known  as  a  breaking  engine. 

This  apparatus  is  a  shallow  oval- shaped  vessel  with 
circular  ends,  divided  lengthwise  by  a  partition  called  a 
mid-feather,  which,  however,  does  not  extend  the  full  length 
of  the  apparatus.  In  one  of  the  two  channels  into  which 
the  vessel  is  thus  divided  a  heavy  roll  is  fitted,  which  is 
provided  with  a  number  of  steel  knives.  On  the  floor  of 
this  channel  there  is  fixed  a  bed-plate,"  also  provided 
with  projecting  knives  which  are  parallel  with  the  knives 


54 


THE  MANUFACTUEE  OF  PAPEE 


in  the  roll.  The  distance  between  the  knives  in  the  roll 
and  those  in  the  "  bed-plate"  may  be  altered  as  required 
by  means  of  an  adjusting  screw.  In  the  other  channel  of 
the  breaking  engine  there  is  fitted  a  "  drum-washer,"  which 
serves  for  the  removal  of  the  dirty  water  from  the  machine. 
This  drum  is  divided  into  sections  by  means  of  partitions 
which  reach  from  the  centre  to  the  circumference.  The 


Fig.  1 1 . — A  Breaking  and  Washing  Engine. 

surface  of  the  "  drum- washer  "  consists  of  a  fine  brass  wire 
cloth  supported  by  a  coarser  material  placed  underneath. 

The  breaking  engine  is  half  filled  with  clean  water,  and 
the  rags  are  thrown  into  the  engine  until  it  is  suitably 
filled.  The  rotation  of  the  heavy  roll  causes  the  mixture 
of  rags  and  water  to  circulate  round  the  vessel,  the  floor  of 
which  is  so  constructed  that  the  pulp  is  drawn  between  the 
roll  and  "  bed-plate  "  and  discharged  over  the  "  back-fall," 
which  is  that  portion  of  the  sloping  floor  behind  the 

bed-plate." 


THE  MANUFACTURE  OF  PAPER  FROM  RAGS 


The  "drum-washer  "  rotates  with  its  surface  in  contact 
with  the  mixture  in  the  engine,  so  that  the  dirty  water 
passes  through  the  wire  cloth  and  is  caught  in  the  curved 
sections  or  buckets  inside  the  drum  and  discharged  into  a 
trough  adjacent  to  the  centre,  and  thereby  conveyed  away 
from  the  engine.  Clean  water  is  allowed  to  run  into  the 
vessel  at  one  end  while  the  dirty  water  is  discharged  by 
means  of  the  ''drum-washer."  At  the  same  time  the  rags 
are  broken  up  by  means  of  the  knives  on  the  roll,  so  that  when 
the  rags  are  sufficiently  washed,  a  process  which  usually 
occupies  four  hours,  they  are  also  partially  disintegrated. 

Blcacldnfj. — The  clean  disintegrated  rag  is  next  bleached 
by  means  of  ordinary  bleaching  powder  solution.  Bleaching 
powder  is  a  substance  prepared  by  the  action  of  chlorine 
gas  on  dry  slaked  lime,  resulting  in  the  formation  of  a  com- 
pound which  has  the  property  of  bleaching  or  "  whitening" 
vegetable  matters.  The  clear  solution  obtained  by  treating 
the  powder  with  water  is  utilised  by  the  paper-maker  for 
bleaching  the  rag  pulp. 

Various  methods  are  used  for  this  purpose.  Sometimes 
the  requisite  volume  of  clear  bleach  liquor  is  added  to  the 
pulp  in  the  breaker,  and  the  material  kept  in  constant 
circulation  until  the  operation  has  been  completed.  In 
other  cases  the  broken  pulp  is  transferred  to  a  "potcher," 
which  is  a  vessel  similar  in  shape  to  the  breaker,  but  merely 
provided  with  paddles  for  keeping  the  pulp  in  circulation, 
and  bleached  by  the  addition  of  chloride  of  lime  solution. 

Another  method  frequently  adopted  is  to  discharge  the 
pulp  from  the  breaker,  immediately  after  the  addition 
of  the  bleach,  into  brick  or  cement  tanks,  alloAving  the 
bleaching  action  to  proceed  spontaneously  without  pro- 
longed agitation. 

In  some  instances  the  process  is  hastened  by  adding 
dilute  sulphuric  acid  to  the  pulp  after  the  bleach  liquor  has 


56 


THE  MANUFACTURE  OF  PAPER 


been  run  in,  or  by  heating  the  mixture  with  steam.  For 
high-class  papers  such  devices  as  this  are  seldom  resorted 
to,  as  experience  shows  that  the  colour  of  pulp  bleached  by 
drastic  methods  does  not  maintain  a  high  standard. 

The  pulp  is  then  thoroughly  washed  in  order  to  remove 
every  trace  of  residual  bleach,  and  also  the  soluble  com- 
pounds which  have  been  formed  during  the  operation. 
Very  large  quantities  of  water,  clear  and  free  from  suspended 
dirt,  are  necessary.  In  some  mills  any  excess  of  bleach  is 
neutralised  by  the  use  of  an  "  antichlor  "  such  as  sodium 
hyposulphite,  or  sodium  sulphite,  but  the  best  results  are 
undoubtedly  obtained  when  the  quantity  of  chemicals 
used  is  kept  at  a  minimum. 

If  the  pulp  is  bleached  in  a  breaker  or  potcher,  the  wash- 
ing is  effected  by  the  aid  of  the  drum-washer.  With  pulp 
treated  in  steeping  tanks,  fresh  water  is  allowed  to  percolate 
or  drain  slowly  through  the  mass. 

Electrolytic  Bleaching. 

The  substitution  of  a  sodium  hypochlorite  solution  for 
the  ordinary  calcium  hypochlorite  solution  obtained  from 
common  bleaching  powder  has  been  the  aim  of  specialists 
for  many  years.  As  early  as  1851  a  patent  was  taken  out 
by  Charles  Watt  for  decomposing  chlorides  of  the  alkali 
metals  and  the  formation  of  hypochlorites.  It  was  not 
until  1886  that  a  practical  method  was  devised  for  producing 
an  electrolysed  solution  of  salt,  but  in  that  year  Hermite 
introduced  a  continuous  process  in  which  an  electrolysed 
solution  having  a  strength  of  three  grammes  chlorine  per 
litre  was  passed  continuously  into  the  potcher. 

Many  patents  for  the  electrolysis  of  salt  have  been  taken 
out  during  the  last  twenty  years,  of  which  the  Bird- 
Hargreave  process  is  in  operation  in  England,  the  Ehodin 
process  in  America,  the  Siemens  and  Halske  in  Norway, 


ELECTEOLYTIC  BLEACHING 


and  the  Oettel  and  Haas  apparatus  in  Germany.  The 
figures  relating  to  the  latter  apparatus  may  be  mentioned 
as  typical  of  the  present  condition  of  electrolytic  bleaching. 
The  apparatus  consists  of  a  narrow  rectangular  trough 
divided  into  a  number  of  chambers  through  which  a  solution 
of  brine  flows  at  a  constant  and  steady  rate.  The  electric 
current  is  passed  through  the  solution  by  suitable  electrodes, 
the  temperature  being  kept  down  by  means  of  a  cooling 
coil.  The  cost  of  producing  the  bleach  liquor  as  given  by 
the  inventors  of  the  apparatus  from  the  results  of  actual 
working  are  shown  in  the  following  table  : — 

Table  giving  Analysis  of  Cost  for  Pkoducixg  Bleach 
Liquor. 

Capacity  of  tank      .       .       .    750  Utres  =  166  gallons. 
Strength  or  density  of  brine    .    1*5  Beaume,  or  23  Twaddell. 
286  lbs.  of  common  salt  required  for  166  gallons. 


Hours  worked 

2 

4 

6 

8 

10 

12 

Grammes  of  chlorine 

per  litre  produced 

4-35 

7-38 

9-9 

12-42 

14-31 

16-20 

Temperature   C.  of 

brine  during 

operation 

20 

21 

20 

21 

20 

20 

Amperes  of  110  volts 

55 

50 

46 

52 

47 

43 

Power  in  h.p.  hours 

16 

31 

45 

61 

75 

89 

Cost  of  the  h.p.  at 

'22(1.     per  h.p. 

hour  . 

6|</. 

lOrZ. 

\s.  l^d. 

Is.  4hd. 

Is.  Ihd. 

Cost  of  salt 

Is.  6d. 

Is.  6d. 

Is.  6d. 

Is.  6d. 

Is.  6(f. 

\s.  6r/. 

Total  cost 

Is.  9^d. 

2s.0id. 

2s.  4d. 

2s.  l\d. 

2s.  lOhd. 

3s.  l^d. 

Total   chlorine  ob- 

tained in  kilos. 

3-262 

5*535 

7-425 

9-315 

10-732 

12-150 

Cost  of  chlorine  per 

kilo.     .       .  . 

6'6d. 

4y. 

S^d. 

3-4</. 

3- 2d. 

'6d. 

Salt  used  per  kilo. 

chlorine 

35 

20 

15 

12 

10 

9 

The  above  costs  have  been  estimated  on  prices  as  follows  : — 

Coal        .       .       .    10s.  per  ton. 

Salt        .       .       .12s.  per  ton. 
After  12  hours  the  166  gallons  (750  litres)  are  converted  into  electro- 
lytic bleach  liquor  containing  26|  lbs.  of  active  chlorine  (12-15  kilos.). 


58 


THE  MANUFACTURE  OF  PAPER 


Beating. — Although  the  rags  are  reduced  by  the  breaking 
engine  to  a  condition  of  fibrous  Hnt,  called  "  half-stuff," 
they  are  not  fit  for  conversion  into  paper.  They  have  to 
be  beaten  in  special  machinery  until  a  complete  separation 
of  the  single  fibres  has  been  effected,  and  this  process  is 


Fig.  12. — Oettel  and  Haas'  Apparatus  for  the  manufacture  of 
Electrolytic  Bleach  Liquor. 


rightly  regarded  by  many  paper-makers  as  the  most 
imjDortant  stage  of  manufacture. 

The  beating  engine  is  similar  in  construction  to  the 
breaking  engine,  but  there  are  certain  essential  differences 
in  arrangement  and  manipulation.  There  is  usually  no 
drum-washer ;  the  roll  contains  a  large  number  of  knives 
which  are  fixed  in  clumps  or  sets  of  three  round  the 
circumference  ;  the  lowering  of  the  roll  upon  the  bed-plate 
is  carefully  watched  and  controlled,  and  the  desired  effects 


BEATING 


59 


are  only  obtained  by  strict  attention  to  the  condition  of  the 
23ulp  during  the  whole  process. 

The  beater  is  first  partially  filled  with  water,  and  the 
drained  half-stuff  added  gradually  until  the  "  furnish,"  a 
convenient  term  applied  to  the  contents  of  the  engine,  has 


i^^iG.  13.— The  "  Hollander"  Beating  Engine. 

the  proper  consistency,  which  varies  according  to  the  nature 
and  quality  of  paper  required. 

The  mass  is  circulated  steadily  round  the  engine  by  the 
action  of  the  beater  roll,  which  is  lowered  from  time  to  time 
until  the  distance  between  the  knives  on  the  roll  and  those  on 
the  bed-plate  has  been  set  to  the  desired  adjustment.  This 
lowering  of  the  roll  and  its  proper  adjustment  call  for  the 
greatest  care. 

Influence  of  the  Beati7ifj.~The  importance  of  this  opera- 
tion can  easily  be  judged  from  one  or  two  specific  examples. 


60 


THE  MANUFACTURE  OE  PAPER 


In  the  case  of  rag  papers  the  two  extremes  of  variation  are 
represented  by  the  ordinary  blotting  paper  on  the  one 
hand  and  a  hard  strong  writing  paper  known  as  a  loan  on 
the  other.  Now  the  great  difference  in  these  papers  maybe 
traced  to  the  careful  selection  of  the  rag  and  the  treatment 
in  the  beater  as  the  two  primary  causes  of  the  final 
results. 

For  blotting  papers  it  is  essential  that  the  rags  should 
be  old  and  tender.  In  the  beating  operation  subsequent  to 
the  usual  boiling  and  bleaching  processes  the  half-stuff  is 
beaten  quickly  with  sharp  knives,  the  roll  being  lowered 
soon  after  the  engine  is  filled,  so  that  the  beating  is  finished 
in  about  one  to  one  and  a  half  hours. 

For  the  strong  writing  paper  new  strong  rags  are  selected. 
In  the  beating  process  the  knives  used  are  dull,  the  roll  is 
lowered  slowly  and  cautiously,  and  the  beating  goes  on  for 
eight  to  ten  hours. 

The  effect  of  such  difference  in  treatment  is  easily  seen 
by  examination  of  the  fibres  of  the  papers  under  the  micro- 
scope. In  the  first  case  the  fibres  appear  short  with  clean 
cut  ends,  the  shape  little  distorted,  the  structure  well 
defined,  bearing  a  strong  resemblance  to  the  unbeaten 
material.  In  the  case  of  the  well-beaten  paper  the  ends  of 
the  individual  fibres  appear  to  be  drawn  or  frayed  out, 
the  fibres  do  not  possess  the  sharp  well-defined  outline 
characteristic  of  blotting  paper;  they  are  partly  split  up 
into  fibrillae  which  lie  together  in  a  confused  mass. 

In  the  blotting  paper  these  effects  are  produced  because 
the  knives  beiug  sharp  cut  up  the  material  quickly,  and 
in  the  writiug  paper  because  the  dull  "tackle"  tends  to  draw 
out  the  fibres  and  tear  them  up  lengthwise. 

The  practical  result  is  a  spongy,  soft,  and  bulky  blotting 
and  a  hard,  strong,  heavy  writing  paper.  Of  course  the 
great  difference  between  a  blotting  and  a  writing  paper  is 


BEATING 


61 


not  all  due  to  this  one  operation,  but  is  obtained  by  a  series 
of  operations,  of  which  one  of  the  most  important  is,  how- 
ever, the  beating. 

Colouring  the  Paper. — The  pulp  is  brought  to  any  desired 
tint  by  the  addition  of  mineral  pigments  or  anihne  dyes  to 
the  contents  of  the  engine.  The  latter  soluble  dyes,  however, 
are  seldom  used  for  high-class  rag  papers.  Prussian  blue, 
ultramarine,  and  smalts  are  chiefly  used  for  this  purpose, 
giving  toned  blue,  azure,  and  blue  laid  pa^^ers. 

Making  the  Paver. — The  beaten  pulp,  when  duly  prepared, 
is  run  from  the  engine  into 
store  tanks  known  as  stuff 
chests,  ready  for  the  actual 
manufacture.  The  pulp  pro- 
perly diluted  with  water  is 
strained  through  special 
screens  to  remove  any  in- 
sufficiently beaten  material 
and  any  impurities  present, 
after  which  it  is  run  off  into 
the  vat,  a  square-shaped 
vessel  built  of  wood  or  stone. 

The  apparatus  used  in  forming  the  sheets  is  called  a 
hand  mould.  The  mould  is  a  rectangular  frame  of  mahogany 
upon  which  is  stretched  tightly  a  fine  wire  cloth,  the  surface 
of  the  latter  being  kept  flat  by  a  coarser  wire  cloth  fixed 
underneath,  supplemented  by  wedge-shaped  pieces  of  wood. 
A  second  frame  called  the  deckle  fits  on  to  the  mould  in  such 
a  manner  as  to  form  a  shallow  tray,  the  bottom  of  which  is 
the  fine  wire  cloth. 

The  vatman  takes  up  the  mould  with  both  hands  and 
dips  it  into  the  vat  full  of  pulp  in  a  slanting  position,  draw- 
ing it  through  the  stuff  towards  him  in  a  peculiar  manner 
and  lifting  it  out  from  the  vat  with  a  definite  quantity  of 


62 


THE  MANUFACTUEE  OF  PAPEE 


the  mixture  in  the  frame.  As  the  water  drains  away  from 
the  pulp,  through  the  wire  cloth,  he  imparts  a  shaking 
motion  to  the  mould  in  order  to  cause  the  fibres  to  felt  " 
properly,  this  felting  or  interlacing  of  the  fibres  being  an 
essential  feature  in  the  manufacture  of  a  good  sheet  of  paper. 
When  the  water  has  drained  away  sufficiently  from  the 
pulp,  the  vatman  removes  the  deckle  from  the  mould  and 
passes  the  latter  over  to  the  coucher,  who  takes  the  mould, 
reverses  it,  and  presses  the  contents,  which  may  now  be 
described  as  a  wet  sheet  of  paper,  down  on  to  a  damp  piece 
of  felt,  by  which  means  the  paper  is  transferred  to  the  felt. 
He  returns  the  mould  to  the  vatman,  who  meanwhile  has 
made  another  sheet  with  a  duplicate  mould,  and  then,  having 
laid  a  second  felt  upon  the  wet  sheet  of  paper,  he  proceeds 
to  transfer  the  next  sheet  of  paper  to  the  second  felt.  This 
process  is  continued  until  a  pile  is  formed  consisting  of  wet 
sheets  of  paper  alternated  with  pieces  of  felt. 

The  pile  is  at  once  submitted  to  great  pressure  in  the 
hydraulic  press,  and  the  excess  water  slowly  forced  out, 
while  at  the  same  time  the  sheets  are  com23ressed  and  thus 
"closed  up,"  as  it  is  termed.  When  all  the  excess  water 
has  been  removed  as  far  as  possible,  the  pile  is  taken  away 
and  the  sheets  of  damp  paper  taken  out,  the  felts  being 
placed  in  one  pile  ready  for  further  use,  and  the  sheets  of 
paper  in  a  second  ready  for  the  next  process. 

The  papers  are  put  back  into  the  press  without  felts 
between  the  sheets  and  left  for  some  time.  In  most  cases 
the  sheets  are  turned  round  or  mixed  in  with  the  sheets  of 
another  pile,  before  pressing.  In  this  way  any  unevenness 
or  irregularity  in  the  sheets  is  counteracted  and  a  more 
uniform  result  obtained. 

W^hen  these  changes  are  repeated  several  times  the  paper 
acquires  an  even  texture  and  becomes  firm  and  hard. 

Drying  the  Paper. — The  sheets  are  hung  up  in  the  lofty 


siziNa 


63 


as  the  dryiDg  room  is  called,  upon  poles  or  ropes.  The 
moisture  gradually  evaporates,  and  the  paper  is  thus  dried 
by  exposure  to  air.  In  winter  it  is  necessary  to  warm  the 
air  in  the  loft,  as  the  air  is  then  saturated  with  moisture. 
In  lofts  of  limited  capacity  the  air  is  heated  in  order  to 
hasten  the  process,  but  the  best  paper  is  allowed  to  dry 


Fig.  15. — Apparatus  for  SiziDg  Paper  in  continuous  Eolls. 

naturally,  as  by  this  means  the  shrinkage  is  gradual  and  a 
maximum  strength  is  attained. 

Sizing  the  Paper.-~The  dried  paper  as  it  leaves  the  loft 
is  termed  Waterleaf  because,  being  unsized,  it  readily 
absorbs  water,  and  therefore  before  it  can  be  used  it  must 
be  sized.  For  this  purpose  it  is  dipped  into  a  solution  of 
gelatine,  an  operation  described  as  tuh-sizing  or  animal- 
sizing,  the  former  term  being  used  on  account  of  the  tub  in 
which  the  size  is  kept,  and  the  latter  on  account  of  the  fact 
that  the  gelatine  is  made  from  animal  matter  such  as  hides, 
cartilage,  hoofs,  and  other  refuse. 

Animal  Size. — This  is  prepared  from  hide  pieces,  skins, 


64 


THE  MANUFACTUEE  OF  PAPER 


and  the  like  by  a  simple  process,  which,  however,  requires  a 
good  deal  of  care  in  order  to  obtain  the  best  results.  The 
material  is  first  thoroughly  washed  in  plenty  of  clean  water, 
and  then  heated  with  a  definite  quantity  of  water  in  a 
steam  jacketed  copper  pan.  The  pieces  slowly  dissolve 
until  a  solution  of  gelatine  is  produced,  and  after  the  dirt 
and  impurities  have  settled  to  the  bottom  of  the  pan  the 
clear  liquid  is  drawn  off  into  store  vessels.  There  are  many 
details  of  a  technical  character  to  be  attended  to  in  the 
manufacture  of  good  gelatine,  and  as  the  process  is  expen- 
sive, considerable  attention  is  demanded  at  this  stage  in  the 
completion  of  a  sheet  of  paper. 

The  dry  sheets  of  paper  are  sized  by  the  simple  expedient 
of  dipping,  or  by  the  passage  of  the  paper  through  a  long 
trough.  In  the  first  case  the  workman  takes  up  a  number  of 
sheets  and  dips  the  bunch  into  a  vat  of  size  at  the  proper 
temperature,  about  100°  Fahrenheit.  He  then  allows  the 
surplus  size  to  drain  off,  and  the  sheets  are  submitted  to  a 
slight  pressure  in  order  to  remove  the  excess  of  gelatine  that 
will  not  drain  off. 

In  the  second  case  a  different  method  is  adopted  in  that 
the  sheets  of  paper  are  carried  by  travelling  felts  through  a 
bath  of  heatfed  size,  the  excess  gelatine  being  removed  by 
the  action  of  rubber  or  wooden  rollers  through  which  the 
papers  are  passed  before  leaving  the  apparatus.  The  papers 
are  quickly  and  evenly  sized  by  this  method,  which  is  now 
most  generally  used. 

Glazing. — When  the  sheets  of  paper  are  quite  dry  they 
are  ready  for  glazing,  a  process  which  turns  the  dull  rough 
surface  of  the  sized  sheet  into  a  highly  polished  smooth 
surface  fit  for  use.  The  sheets  are  placed  singly  between 
copper  or  zinc  plates,  and  a  pile  of  these  passed  several 
times  through  heavy  iron  rollers,  great  pressure  being 
applied  to  the  latter  during  the  operation. 


SIZING 


65 


66 


THE  MANUFACTUEE  OF  PAPER 


The  amount  of  polish  imparted  by  this  plate-glazing  pro- 
cess, as  it  is  termed,  can  be  varied  considerably.  With  a 
light  pressure  and  few  rollings,  the  sheet  of  paper  can  be 
turned  out  having  a  fairly  smooth  surface,  and  without  a 
conspicuously  shiny  appearance.  By  employing  a  great 
pressure  and  repeated  rolling  a  much  higher  surface  is 
attainable.  If  the  plates  are  hot  a  still  higher  finish  is 
possible.  Machine-made  rag  papers  are  glazed  usually  by 
means  of  the  supercalender,  which  is  a  stack  of  alternate 
steel  and  paper  rolls  placed  one  above  the  other  in  a 
vertical  position.  The  reel  of  paper  passes  between  these 
rolls  and  becomes  highly  surfaced. 

This  operation  effects  many  changes  in  the  paper,  besides 
imparting  a  good  finish.  The  thickness  of  the  sheet  is 
reduced  by  about  40  per  cent.,  the  fibres  being  compressed 
much  closer  together.  The  tensile  strength  of  the  paper  is 
also  materially  increased,  and  in  every  way  the  paper  is 
improved.  Moderation  is  essential  in  this  as  in  everything, 
because  excess  of  glazing  weakens  a  paper,  rendering  it 
brittle  and  liable  to  crack  when  folded. 

Laid  and  Wove  Papers. — When  certain  papers  are  held 
up  to  the  light  and  carefully  examined  it  will  be  noticed 
that  they  appear  to  contain  delicate  transparent  lines 
running  parallel  with  one  another  at  equal  distances  of 
about  an  inch,  and  that  these  are  intersected  by  similar 
transparent  lines  running  at  right  angles,  which  are  much 
closer  together.  Such  papers  are  known  as  Laid  Papers, 
and  the  peculiar  formation  of  the  transparent  lines  is  due 
to  the  construction  of  the  mould  used  in  the  making.  The 
wire  surface  of  this  mould  consists  of  a  number  of  some- 
what stout  wires  placed  about  one  inch  apart,  interwoven 
with  finer  wires  running  across  and  at  right  angles,  which 
are  threaded  much  closer  together.  When  the  mould  is 
dipped  into  the  vat  and  withdrawn,  the  water  drains  away 


WATEEMAEKS 


67 


from  the  under  surface  of  the  wire,  and  the  moist  pulp 
settles  down  on  the  upper  surface ;  but  since  the  coarser 
wires  project  a  little  from  the  finer  threads,  the  paper  is 
slightly  thinner  along  those  wires,  though  to  an  almost 
infinitesimal  extent,  with  the  result  that  on  drying  the 
sheet  appears  to  contain  transparent  lines. 

Wove  papers  are  so  called  from  the  nature  of  the  mould 
used.  The  surface  of  the  mould  in  this  case 
consists  of  fine  wires  equally  distributed,  being 
woven  in  such  a  manner  that  the  wires  are 
equidistant  from  one  another,  as  in  ordinary 
wire  gauze.  A  wove  paper,  on  being  examined 
in  the  light,  simply  shows  a  number  of  small 
diamond-shaped  spaces,  which  in  the  majority 
of  instances  are  difficult  to  detect. 

The  Watermark. — The  transparent  device 
observed  in  many  papers  when  held  up  to  the 
light  is  known  as  the  watermark,  a  term  pro- 
bably derived  from  the  conditions  existing  at 
the  time  the  sheet  of  paper  is  made  on  the 
mould.  The  effect  is  produced  by  means  of 
a  raised  design  sewn  or  soldered  to  the  surface 
of  the  mould,  the  design  being  fashioned  out 
of  fine  wire. 

When  a  mould  thus  fitted  with  the  design  is 
dipped  into  a  vat  of  pulp  and  lifted  out,  the  water  falls 
through  the  wire,  and  the  pulp  sinks  down  on  to  the  surface 
of  the  mould,  forming  a  replica,  so  to  speak,  of  the  design, 
which  is  easily  seen  when  the  dry  paper  is  held  up  to  the 
light,  because  the  paper  is  thinner  just  at  those  points 
where  the  wires  forming  the  design  come  into  contact  with 
the  wet  pulp. 

Some  of  the  watermarks  are  very  elaborate  and  interesting. 
A   familiar   illustration   of   a  beautiful  design  of  this 

F  2 


Fig.  17.— The 
First  Water- 
in  a  r  k  in 
Paper. 


68 


THE  MANQFACTUEE  OE  PAPER 


description  is  to  be  found  in  the  Bank  of  England  notes. 
As  a  general  rule  the  ordinary  watermark  consists  of  a 
mere  trade  term  such  as  "Vellum,"  "  Zenobia,"  or  of  the 
name  of  the  manufacturer,  such  as  "  J.  Whatman," 
"E.  Batchelor,"  and  so  on.  In  the  earlier  days  of  paper- 
making  many  highly  interesting  designs  were  used,  and 
some  of  these  are  still  extant.  In  fact  many  of  the  names 
by  which  certain  standard  sizes  of  paper  are  known  owe 
their  origin  to  the  watermarks  employed. 

The  earliest  known  watermark  bears  the  date  a.d.  1301, 
being  in  the  form  of  a  globe  and  cross,  as  shown.  Of  equal 
interest  are  those  designs  from  which  certain  papers  are 
called  foolscap,  crown,  pott,  post,  royal,  columbier,  and  so 
on.  The  watermarks  are  now  little  used,  but  the  terms  are 
still  retained,  as  indicating  the  size  of  the  sheet. 

Microscopic  Features  of  Cotton  and  Linen  Fibres. 

The  cotton  fibre  is  about  30  mm.  long,  with  an  average 
diameter  of  '025  mm.  of  tube-like  shape,  and  having  a 
prominent  central  canal.  There  are  no  cross  markings 
on  the  cell  walls,  and  the  ends  of  the  fibre  are  rounded 
off  into  a  somewhat  blunt  point.  It  exhibits  a  marked 
tendency  to  twist  itself,  especially  if  dry,  and  this 
peculiarity  is  readily  observed  with  the  raw  material. 

The  process  of  paper-making  alters  the  characteristic 
structure  of  the  fibre  very  greatly.  The  ends  of  the  fibre  are 
seldom  to  be  seen ;  the  curious  twist  is  less  prominent,  and 
the  fibres  are  torn  and  destroyed.  The  effect  of  the  beating 
process,  for  example,  on  cotton  is  easily  to  be  noticed  by 
comparing  the  fibres  of  a  blotting  paper  under  the  microscope 
with  the  fibres  of  a  baiik  or  loan  paper. 

The  distortions  produced  by  prolonged  .beating  renders 


COTTON  AND  LINEN  FIBRES 


69 


the  determination  of  the  exact  percentage  of  cotton  in  a  rag 
paper  rather  difficult,  but  the  features  to  be  looked  for  are 
the  absence  of  pores,  cross  markings,  the  existence  of  a 
central  canal,  striations  produced  in  many  cases  on  the  cell 


Fig.  is.— Cotton. 


walls  parallel  to  the  length  of  the  fibre.  The  structural 
features  are  more  readily  observed  when  the  fibres  are 
stained  with  a  suitable  reagent.    (See  page  71.) 

The  linen  fibre  has  an  average  length  of  27  mm.  with  a 
diameter  of  '02  mm.  The  raw  flax  is  very  different  from  raw 


70 


THE  MANUFACTURE  OF  PAPER 


cotton  and  is  easily  distinguished.  The  fibre  is  slender  in 
shape,  having  thickened  knots  at  regular  intervals  through- 
out its  length,  the  general  appearance  of  which  may  be 


Fig.  19.— Linen. 


compared  to  a  stick  of  bamboo.  The  central  canal  of  the 
fibre  is  extremely  narrow,  running  like  a  small  thread 
through  the  length  of  the  fibre.  The  cell  walls  are  further 
marked  by  numerous  pores,  which  appear  as  small  dark 
lines  running  from  side  to  side,  but  not  meeting  in  the 
centre. 


COTTON  AND  LINEN  FIBEES 


71 


In  the  treatment  necessary  for  making  paper  these 
characteristics  are  largely  destroyed,  and  while  it  is  quite 
easy  to  ascertain  that  a  paper  is  of  linen,  or  of  cotton,  or 
that  a  paper  is  mainly  cotton  with  a  small  percentage  of 
linen,  yet  there  are  conditions  under  which  it  is  difficult  to 
determine  the  exact  percentage  of  cotton  or  linen  in  a  rag 
paper.  If,  for  example,  a  paper  contains  nearly  equal 
quantities  of  cotton  and  linen,  the  exact  proportions  can- 
not be  determined  closer  than  10  per  cent.,  especially  in 
well-beaten  papers. 

Reagent  for  Staining  Fibres. 

Preparation. — Dissolve  2'1  grams  potassium  iodide  and 
0*1  grams  iodine  in  5  c.c.  of  water.  Mix  this  solution  with 
a  solution  containing  20  grams  of  dry  zinc  chloride  in 
10  c.c.  of  water.  Allow  the  mixture  to  stand  ;  pour  off  the 
clear  liquid  into  suitable  bottles. 

Coloration  Produced. 

Cotton,  linen,  hemp. — Wine  red. 
Esparto,  straw  and  wood  cellulose. — Bluish  violet. 
Meclianical  wood,  unbleached  jute. — Yellow. 
Manila  hemp. — Blue,  bluish  grey  to  yellow. 


CHAPTEK  IV 


esparto  and  straw 

Esparto  Papers. 

The  value  of  Esparto  for  the  manufacture  of  high-class 
printing  and  medium  quality  writing  paper  is  well  known. 
This  material  has  qualities  which  cannot  readily  be 
obtained  from  other  fibres,  such  as  rag  and  wood  pulp. 
It  is  chiefly  used  in  papers  required  for  lithographic 
printing,  books,  and  art  illustration,  since  it  gives  a  sheet 
having  a  good  surface  and  one  which  is  soft  and  flexible. 

The  grass  is  obtained  from  Spain,  Morocco,  Algeria, 
Tunis,  and  Tripoli,  in  which  countries  it  grows  wild, 
requiring  very  little  cultivation.  The  condition  of  the 
crop  is  improved  by  proper  treatment,  and  in  districts 
where  the  grass  is  cut  for  export  as  a  paper-making 
material  atten1]ion  is  given  to  cultivation. 

The  plant  grows  to  a  height  of  three  or  four  feet,  and 
when  mature  the  long  blades  of  grass  curl  up  into  the  form 
of  a  cylinder  resembling  a  piece  of  wire.  The  leaf  consists  of 
two  parts,  the  stalk  and  a  sheath,  which  are  easily  separated 
when  harvested.  The  grass  is  pulled  up  by  hand  and  stacked 
into  heaps  in  order  that  it  may  be  dried  by  the  heat  of  the 
sun,  after  which  process  it  is  carefully  picked  over  for  the 
removal  of  all  extraneous  matter  and  impurities.  It  is  then 
graded,  the  best  sorts  being  kept  for  weaving,  and  the 
remainder  being  sold  for  paper-making.  It  is  packed  up 
into  large  bales  of  about  4  cwt.  capacity,  compressed  into 
small  bulk  by  powerful  presses,  and  shipped  to  England. 


ESPARTO  AND  STE4W 


73 


Esparto  Pulp. — The  first  process  in  the  manufacture  of 
the  paper  is  cleaning.  The  bundles  of  grass  are  opened 
up,  shaken  out,  and  put  through  a  willowing  machine.  This 
consists  of  a  hollow  conical  drum,  the  outer  surface  of  which 
is  a  coarse  wire  cloth.  Inside  the  drum  is  fitted  a  shaft 
provided  with  wooden  teeth,  and  as  the  grass  passes  through 
it  is  tossed  about  and  the  dust  removed.  The  clean  grass 
is  conveyed  by  travelling  belts  to  the  digester  house.  For 
the  production  of  a  high-class  paper  the  grass  is  often 
examined  by  girls,  who  stand  on  either  side  of  the 
travelling  conveyer  and  take  out  any  coarse  root  ends  and 
foreign  material  not  removed  by  the  willowing  machine. 

Boiling. — The  object  of  submitting  esparto  to  chemical 
treatment  is  to  obtain  a  pure  paper-making  fibre  known  as 
cellulose.  The  composition  of  this  raw  material  is  shown 
by  the  following  analysis  : — 

Spanish  Esparto. 


Cellulose   48-25 

Water   9-38 

Aqueous  extract      ....  10"19 

Pectous  matter        ....  26'39 

Fatty  matter   2*07 

Ash   3-72 


100-0 

Yield  of  dry  cellulose  obtained  in 
actual  practice  from  good  raw 
material       .       .       .       .      45  to  48  % 

By  boiling  the  esparto  with  caustic  soda  under  pressure 
for  a  stated  time,  the  non-fibrous  constituents  are  removed, 
leaving  the  cellulose  in  a  more  or  less  pure  form  according 
to  the  severity  of  the  chemical  treatment. 


74 


THE  MANUFACTURE  OF  PAPER 


In  practice  the  grass  is  packed  tightly  into  upright 
stationary  digesters  and  a  definite  quantity  of  caustic 
soda  solution  added,  the  amount  of  chemical  used  being 
equal  to  15 — 18  per  cent,  of  the  weight  of  grass  packed 
into  the  digester.  The  form  of  digester  almost  universally 
employed  is  that  known  as  the  Sinclair's  "  vomiting  "  boiler, 
which  is  constructed  so  that  a  continuous  circulation  of  the 


Fig,  20. — An  Esparto  Duster. 


liquid  is  maintained  by  means  of  what  are  called  "  vomit " 
pipes.  These  are  fitted  to  the  sides  of  the  digester  in  such 
a  manner  that  the  caustic  soda  solution  circulates  from  the 
bottom  of  the  digester,  up  through  the  "  vomit "  pipes, 
and  is  discharged  downwards  upon  the  contents  of  the 
boiler  through  a  perforated  plate  fixed  in  the  upper  part 
of  the  digester.  The  requisite  quantity  of  caustic  soda 
solution  is  placed  in  the  digester,  and  steam  admitted  into 


ESPAKTO  AND  STEAW 


75 


the  bottom  of  the  vessel  while  the  grass  is  being  thrown  in. 
In  this  way  a  much  larger  weight  of  grass  can  be  boiled  at 


Fig.  21. — Sinclair's  "  Vomiting  "  Esparto  Boiler. 

one  operation,  since  the  bulk  is  greatly  reduced  when  the 
grass  has  become  thoroughly  soft  and  wet. 

When  the  boiler  is  loaded  the  inlet  is  closed  up  and  steam 


76 


THE  MANUFACTUEE  OF  PAPER 


turned  on  to  the  full  pressure  of  about  40  or  50  lbs.,  this 
being  maintained  for  a  period  of  about  four  hours.  The  non- 
fibrous  constituents  of  the  esparto  are  gradually  dissolved 
out  by  the  caustic  soda,  and  when  the  operation  is  com- 
pleted the  black  liquor  is  run  off  from  the  digester  into 
large  store  tanks,  and  the  esparto  grass  which  remains  in 

a 


Fig.  22.— a  Porion  Evaporator. 


the  digester  is  then  completely  washed  until  the  soda  is 
almost  entirely  washed  out. 

The  conditions  for  boiling  and  bleaching  esparto  are 
varied  by  the  paper-maker  as  circumstances  require.  A 
maximum  yield  of  fibre  is  obtained  when  the  least  possible 
quantity  of  caustic  soda  is  used,  but  a  larger  percentage  of 
bleaching  powder  may  be  necessary  to  ensure  a  well 
bleached  pulp.    The  use  of  an  excess  of  caustic  soda  is 


ESPAETO  AND  STEAW 


77 


probably  the  general  practice  for  several  reasons,  amongst 
which  may  be  noted  the  advisability  of  guarding  against 
irregularities  in  the  quality  of  the  esparto,  and  consequent 
insufficient  boiling,  as  well  as  the  advantage  of  having  some 
free  caustic  in  the  spent  liquors  to  prevent  the  furring  up 
of  the  tubes  of  the  evaporating  apparatus  in  the  soda 
recovery  department. 

The  following  experiments,  given  by  a  contributor  to  the 
Paper  Trade  Revieiv  some  years  ago,  are  interesting  as 
showing  the  effect  of  varying  proportions  of  caustic  soda 
used  per  unit  of  grass  : — 


Experiments  re  Yield  of  Air-dry  Bleached  Pulp  from  Oran 

Esparto. 

Air-dry  Pulp  containing  10  per  cent,  water. 


No.  of 
Experi- 
ment. 

Esparto. 

Soda  Li(iuor. 

Conditions  of  Boiling. 

Weight 

of 
Air-dry 
Pulp. 
Grams. 

Dry 
Pulp 
on  Dry 
Esparto. 
Per 
cent. 

Bleach- 
ing 

Powcler. 
Per 
cent. 

Wt. 

taken. 
Grams. 

Volume, 
C.C. 

Per 
cent. 
Na2  0. 

Time. 
Hours. 

Temp. 
°C. 

Pres- 
sure. 
Lbs. 

1 

200 

800 

1-58 

3 

142 

55 

87-30 

^3-65 

29-5 

2 

200 

800 

2-13 

3 

142 

55 

80-6" 

40-33 

18-5 

3 

200 

800 

2-69 

3 

142 

55 

72  00 

36-00 

10-5 

Practical  Data  calculated  from  Experiments. 


No.  of 
Experi- 
ment. 

Boil 

Weight  of 
Esparto  to 
give  1  ton 

Pulp. 

Cwts. 

00  per  cent. 
Caustic  Soda 
required  to 
Digest 
Esparto. 
Cwts. 

Bleaching 

Powder 
recpiired  to 
Bleach  ]  ton 
Air-diy  Pulp. 
Cwts. 

For  One  Ton  of 
Esparto  used. 

Time. 
Hours. 

Pies- 
sure. 
Lbs. 

60  per 
cent. 
Caustic. 
Lbs. 

Bleach- 
ing 
Powder. 
Lbs. 

1 

3 

55 

45-8 

4-30 

5-26 

210 

260 

2 

3 

55 

49-5 

6-27 

3-39 

282 

156 

3 

3 

55 

55*5 

8-90 

1-96 

358 

79 

78 


THE  MANUFACTURE  OF  PAPER 


Recovery  of  Spent  Liquor. — As  it  is  possible  to  recover 
75  to  80  per  cent,  of  the  soda  originally  used  in  digesting 
the  esparto,  the  washing  of  the  boiled  grass  is  conducted  on 
scientific  principles  in  order  to  ensure  a  maximum  recovery 
of  soda  at  a  minimum  cost. 

The  recovery  is  effected  by  evaporating  down  the. black 
liquor,  together  with  the  washing  waters,  to  a  thick 
syrupy  mass,  which  can  be  burnt.  The  organic  and 
resinous  constituents  of  the  esparto  which  have  been 
dissolved  out  by  the  caustic  soda,  forming  the  soluble 
soda  compounds,  ignite  readily,  and  during  combustion 
the  organic  soda  compounds  are  converted  more  or  less 
completely  into  crude  carbonate  of  soda. 

It  is  obvious,  then,  that  the  cost  of  recovery  depends  mainly 
on  the  quantity  of  weak  washing  water  which  has  to  be 
evaporated.  Consequently  methods  are  devised  by  means 
of  which  the  grass  is  thoroughly  washed  with  as  little 
water  as  possible,  and  some  of  the  methods  are  very 
ingenious. 

The  spent  liquors  and  washing  waters  are  evaporated  to 
a  small  bulk  in  a  vacuum  multiple  effect  apparatus,  and 
the  thick  liquid  mass  obtained  by  evaporation  is  burnt 
either  in  a  rotary  furnace  or  on  an  ordinary  hearth.  Every 
precaution  is  taken  to  effect  this  operation  with  a  minimum 
quantity  of  coal.  The  burning  off  of  this  mass  results  in 
the  formation  of  a  black  substance  which  is  taken  away 
from  the  furnace  and  allowed  to  char  or  slowly  burn  until 
the  impure  white  soda  ash,  or  carbonate  of  soda,  is 
obtained. 

Two  systems  of  recovery  are  in  general  use,  which 
deserve  a  brief  notice  : — 

Direct  Evaporation. — The  liquors  may  be  evaporated  to 
a  small  bulk  ready  for  incineration  by  treatment  in  long 
shallow  pans  or  furnaces,  the  heat  necessary  for  the  process 


ESPAETO  AND  STRAW 


79 


80 


THE  MANUFACTURE  OF  PAPER 


being  obtained  mainly  from  the  combustion  of  the  thick 
concentrated  liquor.  The  most  familiar  type  of  this  form 
of  apparatus  is  the  Porion  evaporator. 

The  combustion  of  the  concentrated  liquor  is  started  by 
a  coal  furnace  at  one  end  of  the  apparatus.  The  thick 
viscous  mass  catches  fire  and  burns  with  a  fierce  flame,  and 
the  heat  is  utilised  in  evaporating  the  weaker  liquors  which 
flow  continuously  through  shallow  brick  troughs,  the  surface 
of  which  is  freely  exposed  to  the  heat  and  flames  from  the 
hearth  where  the  organic  soda  compounds  produced  in  the 
boiling  of  esparto  are  being  incinerated  and  converted  into 
soda  ash. 

Under  suitable  conditions  this  evaporator  is  most 
economical  in  its  results.  It  can  be  erected  cheaply,  and 
when  all  the  heat  is  fully  used  in  every  possible  direction 
it  can  be  worked  at  a  low  cost  compared  with  the  more 
modern  multiple  effect  evaporators. 

Vacuum  Multiple  Effect  Evay oration. — Advantage  is  taken 
of  the  fact  that  water  boils  at  a  lower  temperature  in  a 
vacuum  than  at  the  ordinary  pressure  of  the  atmosphere. 
There  are  many  forms  of  apparatus  based  on  this  principle, 
amongst  which  the  most  recent  is  Scott's  evaporator.  The 
black  liquor  from  the  boilers  is  pumped  through  tubes  heated 
externally  by  high-pressure  steam.  The  liquor  is  passed 
into  a  chamber  in  which  a  slight  vacuum  is  maintained,  so 
that  immediately  on  entering,  the  liquor  parts  with  a  good 
deal  of  water  in  the  shape  of  steam.  The  steam  liberated 
is  utilised  in  producing  further  evaporation  of  the  partially 
concentrated  liquor,  and  this  operation  is  repeated  several 
times  until  the  concentration  is  effected  to  the  desired 
point. 

In  most  cases  the  actual  incineration  of  the  thick  liquor 
is  carried  out  in  a  rotary  furnace  when  such  an  apparatus 
as  this  is  used. 


ESPARTO  AND  STRAW 


81 


Evaporation  Table. 

Showing  the  volume  of  liquor  obtained  by  evaporating  1,000  gallons 
of  weak  black  lye  of  density  d  to  a  higher  density  D. 


Higher  Density  D  (Twaddell)  at  100°  F, 


iJeusiLy  a 
(at  100°  F.). 

20. 

25. 

30. 

35. 

40. 

45. 

50. 

55. 

60. 

2 

100 

80 

66-6 

57-1 

50 

44-4 

40 

36-3 

33-3 

3 

150 

120 

100 

85-7 

75 

66-6 

60 

54  5 

50 

4 

200 

160 

133-3 

114-3 

100 

88-8 

80 

72-7 

66-6 

5 

250 

200 

166-6 

143 

125 

111-0 

100 

90-9 

83-3 

6 

300 

240 

200 

171-4 

150 

133-3 

120 

109 

100 

7 

350 

280 

233-3 

200 

175 

155-5 

140 

127 

116-6 

8 

400 

320 

266-6 

228-6 

200 

177-6 

160 

145-5 

133-3 

9 

450 

360 

300 

257 

225 

200 

180 

163-5 

150 

10 

500 

400 

333-3 

286 

250 

222 

200 

181-8 

166-6 

Example  : — 1,000  gallons  of  weak  liquor  at  a  density  of  7°  Twaddell 
are  reduced  to  a  volume  of  200  gallons  having  a  density  of  35° 
Twaddell,  or  to  a  volume  of  140  gallons  with  a  density  of  50° 
Twaddell,  by  evaporation. 

Preparation  of  Caustic  Soda. — The  crude  soda  ash 
recovered  from  previous  boiling  operations  is  dissolved  in 
large  lixiviating  tanks  and  extracted  with  hot  water.  The 
clear  solution  obtained  after  all  impurities  have  been  allowed 
to  settle  is  pumped  up  into  the  causticising  tanks,  where 
it  is  converted  into  caustic  soda,  the  loss  due  to  the  amount 
of  soda  not  recovered  being  made  up  by  the  addition  of 
ordinary  soda  ash.  The  causticising  pans  are  large  circular 
iron  vessels  usually  9  feet  diameter  and  8  or  9  feet  deep, 
into  w^hich  a  known  volume  of  the  recovered  carbonate 
of  soda  solution  is  placed. 

A  weighed  quantity  of  ordinary  quicklime  is  then  put 
into  a  perforated  iron  cage  which  is  fixed  inside  the 
causticising  pan  at  such  a  level  that  the  whole  of  the 
lime  is  immersed  in  the  solution.    The  liquor  is  kept  in 

P.  G 


82 


THE  MANUFACTURE  OF  PAPER 


constant  circulation  by  means  of  an  agitator  and  heated  to 
boiling  point,  with  the  result  that  the  chemical  reaction 
sets  in,  the  carbonate  of  soda  being  converted  into  caustic 
soda  and  the  lime  being  thrown  out  as  chalk.  When  the 
operation  is  completed,  the  steam  is  turned  off  and  the 
chalk  allowed  to  settle.  The  clear  liquor  is  carefully 
strained  off  and  pumped  up  into  store  tanks  from  which  the 
required  quantities  are  drawn  off  into  the  digesters  as 
circumstances  demand. 

Washijig. — The  grass  which  has  been  partially  washed  in 
the  digester  is  dug  out  by  the  workmen  and  discharged 
through  a  manhole  fitted  on  one  side  of  the  digester  near 
the  bottom.  It  is  then  conveyed  in  any  convenient  manner 
to  the  breaking  engine,  in  which  the  grass  is  more  com- 
pletely washed.  This  important  machine  has  already  been 
described  on  page  53.  The  floor  of  the  vessel  slopes  slightly 
upward  towards  the  front  of  the  roll  and  falls  suddenly 
behind  the  roll,  in  order  to  promote  a  circulation  of  the 
contents  of  the  engine  round  and  round  the  vessel. 

A  definite  weight  of  boiled  grass  is  thrown  into  the  engine 
together  with  a  large  quantity  of  fresh  water.  The  circu- 
lation of  the  roll  draws  the  mixture  of  pulp  and  water 
between  the  knives,  breaking  it  up  and  at  the  same  time 
discharging  it  behind  the  beater  roll,  and  producing  a 
continuous  circulation  of  the  mixture  in  the  two  sections  of 
the  vessels. 

The  dirty  water  is  continuously  removed  from  the  vessel 
by  means  of  a  "  drum- washer."  This  is  a  large  hollow 
drum,  the  outer  surface  of  which  consists  of  a  fine  wire 
cloth,  the  interior  of  the  washer  being  fitted  with  specially 
curved  scoops.  The  drum- washer  is  lowered  until  it  is  half 
immersed  in  the  mixture  of  pulp  and  water,  and  as  it  rotates 
the  dirty  water  finds  its  way  through  the  wire  cloth,  being 
caught  up  by  the  internal  scoops  and  discharged  through  a 


ESPAETO  AND  STRAW 


83 


pipe  to  a  drain  outside  the  breaking  engine.  At  the  same 
time  fresh  water  is  run  into  the  vessel  at  one  end,  and  the 
continuous  washing  of  the  pulp  thus  effected. 

Bleaching. — The  clean  boiled  grass  is  bleached  by  means 
of  a  solution  of  chloride  of  lime. 

There  are  several  methods  used  for  this  purpose,  each  of 
which  has  special  advantages  of  its  own,  though  this  is 
largely  a  question  of  local  conditions  : — 

(A)  The  pulp  can  be  bleached  in  the  washing  engine 
directly  the  grass  has  been  sufficiently  cleaned.  In  this 
case  the  flow  of  fresh  water  is  stopped  and  as  much  water 
as  possible  removed  by  means  of  the  drum-washer.  The 
drum-washer  is  then  raised  out  of  the  pulp  and  a  known 
volume  of  bleaching  powder  solution  corresponding  to  a 
definite  weight  of  dry  powder  is  added  to  the  contents  of 
the  breaking  engine.  The  amount  used  depends  on  the 
quantity  of  dry  grass  in  the  breaking  engine,  the  usual 
proportion  being  8  to  10  per  cent,  on  the  calculated  air- 
dry  weight  of  raw  grass.  As  the  stuff  circulates  round 
the  engine  the  colour  gradually  changes  from  dark  yellow 
to  white. 

The  process  is  sometimes  hastened  by  blowing  a  small 
quantity  of  steam  into  the  mixture  and  thereby  raising  its 
temperature.  Considerable  care  must  be  exercised  in  using 
heat,  because  pulp  bleached  quickly  by  this  means  is  liable 
to  lose  colour  at  the  later  stages  of  manufacture. 

When  the  pulp  has  been  bleached  to  the  required  extent, 
the  drum-washer  is  again  lowered  into  contact  with  the 
bleached  pulp,  and  the  latter  is  thoroughly  washed  so  as  to  be 
quite  free  from  traces  of  bleach  and  other  soluble  impurities. 

(B)  Esparto  is  often  bleached  in  a  "  Tower  "  bleaching 
engine  which  consists  of  a  tall  cylindrical  vessel  of  9  feet 
diameter,  and  15  or  16  feet  deep,  at  the  bottom  of  which  is 
fixed  a  small  centrifugal  pump. 

a  2 


84 


THE  MANUFACTURE  OF  PAPER 


The  boiled  grass  together  with  sufficient  water  and  clear 
bleaching  powder  solution  is  placed  in  the  engine ;  the 
centrifugal  pump  draws  the  mixture  from  the  bottom  of  the 
vessel  and  discharges  it,  by  means  of  a  large  external  pipe, 
direct  into  the  top  of  the  vessel,  where,  as  it  falls,  it  comes 
into  contact  with  a  circular  baffle-plate,  which  distributes 
the  pulp  evenly  over  the  surface  of  the  mixture  in  the 
vessel.  A  continuous  and  rapid  circulation  is  thus  main- 
tained, and  the  process  is  said  to  be  very  effective.  The 
bleached  pulp  is  subsequently  washed  free  from  any  traces 
of  bleach. 

(C)  Esparto  is  frequently  bleached  by  the  "steeping" 
process.  In  this  case  the  pulp  is  washed  in  the  breaking 
engine,  mixed  with  the  required  quantity  of  bleach,  and  at 
once  discharged  through  the  outlet  pipes  of  the  engine  into 
large  brick  tanks,  where  the  bleach  is  allowed  to  act  quietly 
upon  the  boiled  grass.  This  method  produces  a  pulp  of  good 
colour  and  is  economical. 

Whichever  process  of  bleaching  is  adopted,  it  is  necessary 
to  remove  all  the  by-products  formed  daring  the  process, 
as  these  soluble  by-products  if  left  in  the  mixture  produce 
a  lowering  ofNColour. 

The  presence  of  small  traces  of  bleaching  powder  solution 
can  be  detected  by  the  use  of  starch  and  potassium  iodide 
test  papers.  If  a  handful  of  the  pulp  after  bleaching,  when 
squeezed  out,  does  not  turn  the  test  paper  violet  or  blue, 
then  the  absence  of  any  free  bleach  is  taken  for  granted. 
The  slightest  trace  of  bleach  will  turn  such  test  papers  blue 
or  violet  according  to  the  amount  present.  This  is  the  test 
usually  applied  by  the  men  in  charge  of  the  bleaching 
operations. 

Making  Sheets  of  Esparto  Pulp, — For  convenience  in 
handling,  it  is  usual  to  work  up  the  washed  and  bleached 
pulp  into  the  form  of  moist  sheets.    This  is  effected  on  a 


86 


THE  MANUFACTUEE  OF  PAPER 


machine  known  as  a' "  presse-pate,"  an  apparatus  which 
closely  resembles  the  wet  end  of  a  paper  machine.  It  con- 
sists of  a  set  of  flat  strainers  or  screens,  a  horizontal  wire 
similar  to  the  paper  machine  wire,  provided  with  deckles, 
the  usual  couch  rolls,  and  press  rolls. 

The  pulp  diluted  with  water  is  passed  through  the  screens 
and  on  to  the  horizontal  wire,  where  it  is  formed  into  a 
moist  sheet,  the  water  draining  away  from  the  wire,  and 
also  being  removed  by  vacuum  pumps.  The  thick  sheet  of 
pulp  is  carried  through  the  couch  rolls  and  press  rolls,  being 
finally  wound  up  on  a  wooden  roller  at  the  end  of  the 
machine.  In  this  moist  condition  it  is  ready  for  use  in  the 
mill. 

Dry  Esparto  Pulp. — When  the  bleached  pulp  is  intended 
for  export  a  more  elaborate  machine  is  used — to  all  intents 
and  purposes  a  paper-making  machine — by  means  of  which 
the  continuous  sheet  of  moist  pulp  is  dried  and  cut  up  into 
smaller  sheets  of  suitable  size.  These  dried  sheets  are 
packed  up  in  bales  containing  2  cwt.  or  4  cwt.  of  dried 
pulp,  then  wrapped  in  hessian  and  bound  with  iron  wires. 

Other  Methods. — Since  the  yield  of  esparto  pulp  from  the 
raw  material^ is  less  than  50  i^er  cent,  and  it  requires 
45  cwt.  of  grass  to  make  one  ton  of  finished  pulp,  methods 
have  been  devised  for  treating  the  grass  in  the  green  state 
in  the  districts  where  it  is  grown,  but  so  far  nothing  has 
been  done  on  a  large  scale. 

TJie  isolation  of  the  cellulose  by  alkaline  treatment  in  the 
cold  has  been  suggested,  but  the  method  never  passed 
beyond  the  experimental  stage.  This  process  was  indeed 
first  mentioned  by  Trabut,  who  many  years  ago  considered 
that  the  removal  of  non-fibrous  constituents  from  fresh 
grass  could  be  readily  accomplished  by  the  less  drastic 
treatment  of  the  esparto  with  alkaline  carbonates  of  soda 
and  potash  at  ordinary  temperatures. 


ESPAETO  AND  STRAW 


87. 


The  production  of  esparto  pulp  hy  bacteriological  fermenta- 
tion is  an  idea  of  later  date.  According  to  the  inventor, 
the  grass  is  crushed  mechanically  by  means  of  rollers  and 
then  immersed  in  sea  water  inoculated  with  special  bacillus 
obtained  from  esparto,  and  gradually  resolved  into  cellulose 
and  soluble  by-products  by  fermentation  which  is  complete 
in  about  eleven  days.  The  commercial  value  of  this  idea 
has  not  yet  been  demonstrated. 

Esparto  Pulp  :  Microscopical  Features. 

The  pulp  of  esparto  when  examined  under  the  microscope 
is  easily  recognised,  first  by  the  characteristic  appearance 
of  the  long  slender  cylindrical-shaped  fibres,  and  secondly 
by  the  numerous  cells  always  present.  These  cells  consist 
of  cuticular  vessels  with  serrated  edges,  and  also  of  small 
pear-shaped  seed  hairs,  the  shape  of  which  is  a  ready  means 
of  identifying  esparto.  An  examination  of  the  transverse 
section  of  the  raw  material  indicates  the  source  of  these 
pear-shaped  vessels. 

Test  for  Esparto  in  Papers. — Paper  containing  esparto 
fibre  may  be  tested  by  means  of  a  weak  solution  of  aniline 
sulphate.  The  suspected  paper  is  gently  heated  in  the  test 
reagent,  and  if  esparto  is  present  the  paper  turns  a  rose-red 
or  pink  colour,  the  depth  of  colour  being  a  measure  of  the 
amount  of  esparto.  Most  of  the  modern  book  papers  are 
prepared  from  chemical  wood  pulp  and  esparto  mixed  in 
varying  proportions,  and  while  this  test  can  be  used  as  a 
means  of  detecting  a  small  or  a  large  proportion  of  esparto, 
a  microscopical  examination  is  required  for  a  more  accurate 
estimation. 

The  proportions  used  by  the  paper- maker  depend  upon 
the  weighing  out  of  the  wood  pulp  and  esparto  more  or  less 
accurately,  while  the  microscopical  test  is  based  upon  the 
relative  proportions  as  represented  by  the  volume  of  fibres 


88 


THE  MANUFACTURE  OF  PAPER 


of  each  class  on  the  glass  slip  placed  under  the  microscope. 
Since  the  wood  pulp  consists  of  a  number  of  broad  flat 
ribbon-like  fibres,  and  the  esparto  of  small  cylindrical  fibres, 


Fig.  25.— Esparto  Pulp. 


considerable  practice  is  necessary  in  making  a  proper 
analysis  of  the  two  constituents  in  paper. 

Straw. 


The  use  of  straw  for  the  manufacture  of  paper  was  first 
brought  prominently  into  notice  about  the  year  1800  by 


STEAW 


89 


Matthias  Koops,  who  published  a  book  printed  on  paper 
made  from  straw,  bat  it  was  not  until  1860  that  this 
material  was  used  in  any  large  quantity. 

Straw  is  now  converted  into  a  bleached  paper  pulp  for 


Fig.  26. — A  Cylindrical  Digester  for  Boiling  Fibre. 


news  and  printings,  and  is  also  utilised  for  the  manufacture 
of  straw  boards. 

The  production  of  a  white  paper  pulp  from  straw  is 
carried  out  in  a  manner  similar  to  that  used  in  the  case  of 
esparto  fibre,  viz.,  by  digestion  with  caustic  soda  under 
pressure  and  subsequent  bleaching.  As  the  straw  contains 
considerable  quantities  of  siliceous  matter,  the  chemical 
treatment  necessary  to  reduce  the  material  to  paper  pulp  is 
more  severe,  a  stronger  solution  of  caustic  soda  being  used, 


90 


THE  MANUFACTURE  OF  PAPER 


and  the  process  of  digestion  being  carried  out  at  a  higher 
temperature. 

For  the  best  quality  of  straw  cellulose,  the  material  is 
cut  up  into  small  pieces  by  machines  which  resemble  an 
ordinary  chaff-cutter,  and  the  knots  taken  out  by  a 
separating  machine.  In  most  cases,  however,  the  whole 
straw  is  simply  cut  up  into  small  lengths  of  about  one  to 
two  inches  long,  and  placed  at  once  in  the  digester.  When 
the  straw  is  contaminated  with  foreign  weeds,  sand,  husks, 
and  similar  substances,  as  is  usually  the  case,  it  is  care- 
fully hand-j)icked  by  girls,  who  remove  these  impurities, 
which  tend  to  produce  particles  of  unbleached  matter  in  the 
finished  pulp.  The  expense  of  this  preliminary  cleaning 
process  is  more  than  compensated  for  by  the  enhanced  value 
of  the  bleached  straw  pulp. 

Digesting. — The  cut  straw  is  boiled  in  rotary  cylindrical 
or  spherical  vessels,  stationary  upright  boilers  of  the  vomit- 
ing type  being  seldom  employed  because  the  circulation  of 
the  caustic  soda  liquor  does  not  take  place  freely  with  straw 
packed  in  the  latter. 

As  the  material  is  very  bulky,  some  of  the  liquor  is  first 
put  into  the  boiler  and  the  steam  admitted  while  the  straw 
is  being  thrown  in.  By  this  means  the  straw  is  softened 
and  reduced  in  bulk,  so  that  a  larger  quantity  can  be  added 
before  the  digester  is  quite  full.  The  full  amount  of  caustic 
soda  is  then  made  up  by  further  additions  of  liquor,  and 
the  contents  of  the  digester  heated  by  high-pressure  steam 
for  four  to  six  hours. 

The  conditions  of  treatment  are  shown  by  the  following 
trial 

Amount  of  straw  .  .  .  5,600  lbs. 
Caustic  soda,  20  per  cent.    .       .    1,120  lbs. 

The  caustic  soda  was  added  in  the  form  of  a  liquor, 


STEAW 


91 


having  a  volume  of  2,012  gallons  and  a  specific  gravity 
of  1-055. 

Time  of  boiling     ....    5  hours. 
Pressure  60  lbs. 

Washing. — The  boiled  straw  is  discharged  into  large 
tanks  placed  below  the  digester  and  washed  with  hot  water, 
the  smallest  possible  quantity  being  used  consistent  with 
complete  washing  in  order  to  prevent  the  accumulation  of 
large  volumes  of  weak  lye.  The  spent  liquor  and  washing 
waters  are  drained  off  into  store  tanks  and  evaporated  in  a 
multiple  effect  apparatus  by  the  same  process  as  that  used 
for  esparto  pulp.  The  last  washings  are  usually  run  away 
because  the  percentage  of  soda  in  them  is  too  small  to  pay 
for  the  cost  of  recovery. 

The  final  washing  of  the  straw  pulp  is  completed  by  the 
use  of  a  breaking  engine  or  potcher.  As  straw  pulp  con- 
tains a  large  proportion  of  cellular  matter  which  cannot  be 
regarded  as  true  fibres,  there  is  always  a  danger  of  con- 
siderable loss  in  yield  if  the  use  of  the  breaking  engine  is 
extensively  adopted,  because  the  short  cells  escape  through 
the  meshes  of  the  drum-washer.  The  washing  is  most 
economically  effected  in  the  tanks  if  a  good  yield  of  pulp  is 
required. 

Separating  out  Knots. — The  broken  pulp  from  the  break- 
ing engines  is  diluted  with  large  quantities  of  water  and 
pumped  over  sand  traps  in  order  to  remove  knots  and 
weeds  which  have  resisted  the  action  of  the  caustic  soda. 
These  traps  consist  of  long  shallow  trays,  perhaps  sixty  to 
eighty  yards  long,  one  yard  wide,  and  nine  inches  deep, 
containing  boards  which  stretch  from  side  to  side,  sloping 
at  an  angle,  and  nailed  to  the  bottom  of  the  trays.  The 
dilute  pulp  flows  through  the  trays,  leaving  the  heavy 
particles,  knots,  and  foreign  matter  behind  the  sloping 


92 


THE  MANUFACTUKE  OF  PAPER 


boards,  and  finally  passes  over  the  strainers,  which  retain 
any  large  coarse  pieces  still  remaining. 

Making  Sheets  of  Pulp. — The  mixture  from  the  strainers 
contains  a  large  excess  of  water  which  has  to  be  removed 
before  the  pulp  can  be  bleached.  For  this  purpose  a  wet 
press  machine  (see  page  103)  or  a  presse-pate  (see  page  85) 
is  employed,  and  the  wet  sheets  of  pulp  are  then  ready  for 
bleaching. 

Bleaching. — The  process  by  which  the  pulp  is  bleached  is 
exactly  similar  to  that  used  for  treating  esparto. 

From  1870  to  1890  large  quantities  of  straw  were  used 
for  the  manufacture  of  newspaper  in  conjunction  with 
espai'to  and  wood  pulp,  but  the  price  of  the  material 
was  gradually  advanced  so  that  it  could  not  be  used  with 
advantage,  especially  as  the  production  of  wood  pulp  gave  a 
material  which  was  much  cheaper,  and  which  could  be 
utilised  at  once  without  chemical  treatment. 

In  the  manufacture  of  newspaper  the  tendency  during 
recent  years  has  been  to  make  the  paper  mill  operations  as 
mechanical  as  possible  and  to  dispense  with  the  preliminary 
operations  which  are  essential  for  the  manufacture  of  half- 
stuff,  the  chemical  processes  being  left  in  the  hands  of  the 
pulp  manufacturers. 

The  manufacture  of  straw  cellulose  is  now  practically 
confined  to  Germany,  but  small  quantities  of  the  bleached 
straw  cellulose  are  imported  because  the  pulp  imparts 
certain  qualities  to  paper  which  improve  it,  notably  in 
making  cheap  printing  papers  harder  and  more  opaque. 

Microscopical  Features  of  Straw. 

The  paper  pulp  obtained  from  straw  consists  of  a  mixture 
of  short  fibres  together  with  a  large  proportion  of  oval- 
shaped  cells.  The  fibres  are  short  and  somewhat  resemble 
esparto,  but  the  presence  of  the  smaller  cells  is  a  sure 


MICROSCOPICAL  FEATURES  OF  STRAW  93 


indication  of  the  straw  pulp.  The  fibres  themselves  closely 
resemble  the  fibres  of  esparto,  but  as  a  rule  the  latter 
are  long  slender  fibres,  while  the  straw  fibre  is  very  often 
bent  and  twisted  or  slightly  kinked. 


Fig.  27. — Straw. 

The  only  method  of  distinguishing  between  straw  and 
esparto  is  by  examination  with  the  microscope.  There  is  no 
chemical  reagent  known  which  will  produce  a  colour  reaction 
on  a  paper  containing  straw  that  will  serve  to  distinguish  it 
from  a  paper  containing  esparto.    If  such  papers  are  gently 


94 


THE  MANUFACTUEE  OF  PAPEE 


heated  in  a  weak  solution  of  aniline  sulphate  a  pink  colour 
is  slowly  developed,  the  intensity  of  which  is  to  some 
extent  a  measure  of  the  amount  of  straw  or  esparto 
present. 

Straw  and  esparto  are  usually  described  in  text-books 
under  one  heading,  partly  because  the  fibres  possess  strong 
resemblances  in  physical  and  chemical  constitution,  and 
partly  because  the  methods  of  manufacture  are  identical. 
At  the  same  time  the  qualities  of  the  two  pulps  are  so 
different  that  they  cannot  be  used  indiscriminately,  the 
one  for  the  other.  Straw  cellulose  cannot  be  utilised  in 
the  place  of  esparto,  particularly  for  light  bulky  papers. 
Hence  in  magazine  and  book  papers  containing  a  fibre  which 
gives  a  pink  coloration  with  aniline  sulphate  it  is  fairly 
safe  to  assume  that  esparto  pulp  is  present. 


CHAPTEK  V 


wood  pulp  and  wood  pulp  papers 

The  Manufacture  of  Mechanical  Wood  Pulp. 

Wood  is  converted  into  pulp  suitable  for  the  manufacture 
of  paper  by  methods  which  produce  two  distinct  varieties. 
The  first  is  mechanical  wood  pulp,  so  called  because  it  is 
made  by  a  purely  mechanical  process.  The  second  is  termed 
chemical  wood  pulp  from  the  fact  that  the  material  is  sub- 
mitted to  chemical  treatment. 

Ground  Wood  and  Cellulose. — The  two  varieties  of  pulp  are 
sometimes  distinguished  by  the  use  of  the  terms  ground  wood 
and  cellulose.  In  the  former  case  the  description  implies  a 
product  consisting  of  pulp  obtained  by  grinding  wood  into 
a  fibrous  condition,  while  in  the  second  the  word  suggests 
a  purified  chemical  product  freed  from  the  resinous  and 
non-fibrous  constituents  found  in  wood.  This  is,  in  fact,  the 
essential  difference,  for  mechanical  wood  pulp  consists  of 
fibres  which  have  been  torn  away  from  wood  by  means  of  a 
grindstone  ;  it  differs  but  slightly  in  chemical  composition 
from  the  original  raw  material  and  contains  most  of  the 
complex  substances  natural  to  wood.  Chemical  wood  pulp, 
on  the  other  hand,  consists  of  fibre  isolated  from  wood  in 
such  a  manner  that  the  complex  non-fibrous  substances  are 
more  or  less  entirely  removed.  The  difference  between 
these  two  pulps  is  shown  in  the  following  approximate 
analysis  of  spruce  wood,  and  of  the  pulp  derived  from  it. 
The  composition  of  the  mechanical  pulp  is  practically 
identical  with  that  of  the  wood  itself. 


96 


THE  MANUFACTUEE  OE  PAPER 


Composition  of  Spruce  Wood,  and  of  Chemical  Wood 
Pulp  (Spruce). 


w  ooa 

Chemical 

(Spruce). 

Wood  Pulp. 

Cellulose 

530 

88-0 

Resin  .... 

1-5 

0-5 

Aqueous  Extract . 

2-0 

0-5 

Water  .... 

120 

8-0 

Lignin  .... 

SO'o 

2-5 

Ash      ...  . 

Oo 

0-5 

100-0 

100-0 

The  use  of  mechanical  wood  pulp  is  generally  confined  to 
the  manufacture  of  news,  common  printings  and  packing 
papers,  cardboards,  and  boxboards.  It  possesses  very  little 
strength,  quickly  discolours  when  exposed  to  light  and  air, 
and  gradually  loses  its  fibrous  character.  The  chemical 
wood  pulp  is  a  strong  fibre,  from  which  high-class  papers 
can  be  manufactured,  the  colour  and  strength  of  which 
leave  little  to  be  desired. 

Species  of  Wood. — The  woods  most  commonly  used  for  the 
manufacture  of  wood  pulp  belong  to  the  order  Coniferae,  or 
cone-bearing  trees.  In  Europe  the  spruce  and  silver  fir 
are  the  chief  species,  while  in  America  spruce,  balsam, 
pine,  and  fir  are  employed.  The  harder  woods,  such  as 
hemlock,  beech,  larch  and  others,  are  not  converted  into 
pulp  by  the  mechanical  process. 

Timber  Operatio7is. — The  trees  are  cut  down  in  the  early 
part  of  winter  by  gangs  of  men  specially  trained  to  the  work. 
The  organisation  of  a  lumber  camp  when  the  operations  are 
of  an  extensive  character  is  very  complete  and  carefully 
arranged,  every  detail  being  attended  to  in  order  to  get  out 
the  wood  as  cheaply  and  expeditiously  as  possible.  The 


WOOD  PULP  AND  WOOD  PULP  PAPEES  97 


branches  and  small  tops  are  removed  from  the  trees  when 
they  are  fallen,  and  the  trunks  cut  into  logs  of  12,  14,  or 
16  feet  in  length,  and  afterwards  piled  up  on  the  banks  of 
the  nearest  river,  or  on  the  ice,  ready  for  the  breaking  up 
of  the  winter. 

As  soon  as  the  ice  breaks  up  and  the  rivers  become 
navigable  the  logs  are  floated  down  to  their  destination, 
in  some  cases  hundreds  of  miles  from  the  scene  of 
operations.  Where  rivers  are  not  available  the  timber  is 
brought  out  by  horses  or  bullocks,  or  by  means  of  a  light 
railway. 

Log  Cutting. — As  the  timber  arrives  at  the  mill  it  is 
carefully  measured,  both  as  to  its  diameter  and  length,  in 
order  that  a  record  may  be  kept  of  the  quantity  used. 
Some  of  the  logs  are  piled  up  in  the  storeyard  for  use  in 
the  winter,  and  the  remainder  converted  into  pulp  day  by 
day.  The  logs  are  first  cut  into  short  pieces  about  2  feet 
long  by  means  of  a  powerful  circular  saw,  the  arrangements 
for  this  work  being  devised  so  as  to  keep  down  the  cost  of 
labour  as  much  as  possible.  All  waste  pieces  are  thrown 
aside  to  be  utilised  as  fuel. 

Barking. — The  bark  on  the  logs  is  removed  in  one  or  two 
ways.  Much  of  it  is  knocked  off  during  the  transfer  from 
the  forest  to  the  mill,  but  even  then  the  wood  requires  to 
be  cleaned.  In  Norway  and  Sweden  the  wood  is  treated  in 
a  tumbler  or  a  barker,  while  in  America  and  Canada  the  use 
of  the  tumbler  is  practically  unknown. 

The  barker  consists  of  a  heavy  iron  disc  fitted  with 
knives,  usually  three  in  number,  which  project  from  the 
surface  of  the  disc  about  half  or  three-quarters  of  an  inch. 
The  barker  rotates  in  a  vertical  position,  and  the  short 
pieces  of  wood  are  brought  one  by  one  into  contact  with  the 
disc  in  such  a  manner  that  the  bark  is  shaved  off  by  the 
knives.    The  machine  is  provided  with  conveniences  for 

p.  H 


98 


THE  MANUFACTURE  OF  PAPER 


pressing  the  wood  against  the  disc  and  for  turning  the  logs 
as  they  are  barked. 

The  machine  is  encased  in  a  strong  cast-iron  cover,  and 
all  the  bark  shaved  off  is  carried  away  by  the  strong  current 


Fig.  28. — A  Pair  of  Barkers  for  removing  Bark  from  Logs 
of  Wood. 

of  air  set  up  by  the  rapid  motion  of  the  disc,  and 
subsequently  burnt. 

The  tumbler  system  is  quite  different.  In  this  case  the 
short  pieces  are  thrown  into  a  large  circular  drum  with  hot 
water,  and  the  bark  taken  off  by  the  friction  of  the  pieces 
as  the  drum  rotates.    The  loss  of  material  is  of  course  less 


WOOD  PULP  AND  WOOD  PULP  PAPEES  99 


in  this  process,  but  the  wood  is  not  cleaned  quite  so 
effectively. 

The  wood  at  this  stage  can  be  used  either  for  the  manu- 


FiG.  29. — View  of  Horizontal  Grinder  (a),  with  Section  (b). 


facture  of  mechanical  or  chemical  pulp.  As  a  general  rule 
the  pieces  are  taken  indiscriminately  for  either  process,  but 
sometimes  the  wood  is  sorted  out,  the  clean  stuff  free  from 
knots  and  blemishes  being  reserved  for  high  quality  chemical 
pulp. 

H  2 


100 


THE  MA^'UFACTURE  OF  PAPER 


Grinding. — The  main  feature  of  the  grinding  process  is 
the  attrition  of  the  wood  when  held  against  the  surface  of  a 
rapidly  revolving  grindstone,  the  fibres  as  they  are  rubbed 
off  being  instantly  carried  away  from  the  stone  by  a  current 
of  water.  A  complete  description  of  the  machines  used  and 
the  modifications  of  the  process  practised  by  manufacturers 
is  impossible  in  this  book,  but  the  following  points  will  be 
sufficient. 

The  machine  consists  of  a  large  grindstone  about 
54  inches  in  diameter,  and  27  inches  thick.  It  rotates 
in  a  vertical  or  in  a  horizontal  position  at  a  high  speed. 
The  stone  revolves  inside  a  casing  which  is  provided 
with  a  number  of  j)ockcts,  so  called,  into  which  the  pieces  of 
wood  are  thrown  at  regular  intervals,  as  fast  as  the  wood  is 
ground  by  the  friction  of  the  stone. 

A  continual  stream  of  water  playing  upon  the  surface  of 
the  stone  washes  away  the  pulp  into  a  tank  or  pit  below  the 
machine. 

The  quality  of  the  pulp  may  be  varied  by  the  conditions 
under  which  it  is  made.  By  limiting  the  proportion  of 
water  so  that  the  wood  remains  in  contact  with  the  stone 
for  a  longer  time  the  temperature  of  the  mass  in  the  pockets 
rises.  Such  hot  ground  jmlj),  as  it  is  termed,  is  tough  and 
strong. 

When  the  fibres  are  washed  away  from  the  stone  as  fast 
as  they  are  produced  the  temperature  does  not  rise,  and  cold 
ground  pulp  is  made,  which  is  not  characterised  by  the 
somewhat  leathery  feel  of  the  pulp  made  at  the  higher 
temperature. 

The  surface  of  the  stone  plays  an  important  part  also.  If 
the  stone  is  smooth  the  wood  is  rubbed  away  slowly,  but  if 
the  surface  has  been  roughened  and  grooved  by  means  of  a 
special  tool  the  fibres  are  torn  away  quickly.  In  the  first 
case  the  pulp  comes  from  the  stone  in  a  finely-ground  state 


WOOD  PliLP  AND  WOOD  PULP  PAPER^^  lOl 


and  in  a  uniform  condition,  while  in  the  second  the  pulp  is 
coarse  and  chippy. 

The  output  of  the  machine  is,  however,  much  increased 
by  the  use  of  sharp  stones  and  by  the  application  of  con- 
siderable pressure  to  the  blocks  of  wood. 


Fig.  30. — A  A^ertical  Grinder  for  making  Hot  Ground  Mechanical 
Wood  Pulp. 

Screeninfj. — The  mixture  of  whaler  and  pulp  leaving  the 
grinder  falls  into  a  tank  below  the  stone,  all  large  chips 
being  retained  by  means  of  a  perforated  plate.  The  finer 
pulp,  still  too  coarse  for  use,  is  then  pumped  to  the  screens, 
which  serve  to  remove  all  chippy  and  coarse  fibres  and 


102 


THE  MANUFACTUEE  OF  PAPER 


produce  a  uniform  material.  The  shaking  sieve  consists 
of  a  shallow  tray,  the  bottom  of  which  is  a  brass  plate  or 
series  of  plates  perforated  with  small  holes  or  slits.  The 
pulp  flows  on  to  the  tray,  which  is  kept  in  a  state  of  violent 
agitation,  the  fine  pulp  passing  through  the  holes  and  the 
coarser  pieces  working  down  to  the  lower  edge  of  the  tray 


Fig.  31. — Centrifugal  Screen  for  Wood  Pulp. 


into  a  trough  which  carries  them  away.  The  flat  screen 
is  somewhat  different  in  construction,  but  the  principle  of 
separation  is  the  same.  It  consists  of  brass  perforated 
plates  forming  the  bottom  of  a  shallow  cast-iron  tray, 
continually  agitated  by  means  of  cams  fixed  to  the  under 
surface  of  the  trays. 

The  centrifagal  screen  is  a  cage  made  of  finely  perforated 


WOOD  PULP  AND  WOOD  PULP  PAPEBS 


103 


brass  sheeting  which  revolves  at  a  very  high  rate  of  speed 
inside  a  circular  cast-iron  vessel.  The  pulp  flows  into  the 
interior  of  the  cage,  the  fine  fibres  being  forced  through 
the  screen  by  the  centrifugal  action  of  the  machine,  and  the 
coarse  material  is  retained. 

Wet  Pressing. — The  pulp  leaving  the  screens  is  mixed 
with  such  a  large  quantity  of  water  that  it  is  necessary 


Fig.  32. — Section  of  Centrifugal  Screen  for  Wood  Pulp. 


to  concentrate  it.  This  is  effected  by  means  of  the  wet 
press  machine  (Fig.  41).  The  pulp  and  water  are  pumped 
into  a  wooden  box  in  which  revolves  a  large  hollow 
drum,  the  surface  of  this  drum  consisting  of  a  fine  wire 
cloth  of  about  60  or  70  mesh.  The  drum  is  not  entirely 
immersed  in  the  mixture,  so  that  as  it  rotates  the  pulp 
forms  a  skin  or  thin  sheet  on  the  surface,  and  the  water 
passes  away  through  the  wire  into  the  interior  of  the 


104 


THE  MANUFACTUEE  OF  PAPER 


hollow  drum.  The  drum  carries  the  thin  sheet  out  of  the 
box  and  above  the  level  of  the  mixture  until  it  comes  into 
contact  with  an  endless  blanket  or  felt,  which  is  pressed 
against  that  part  of  the  drum  not  immersed  in  the  liquid. 

By  this  means  the  thin  sheet  is  transferred  to  the  felt 
and  carried  between  squeezing  rolls  to  the  finishing  rolls. 
The  felt,  carrying  on  its  upper  surface  the  thin  sheet  of  pulp, 
passes  between  two  rolls,  usually  16  to  20  inches  in 
diameter,  the  upper  being  made  of  wood  and  the  lower 
one  of  cast  iron.  The  pulp  adheres  to  the  upper  drum  and 
the  felt  passes  round  the  lower  drum  back  to  the  box  con- 
taining the  mixture  of  pulp  and  water  ;  the  thin  sheet  is 
continuously  wound  on  the  upper  roll  until  a  certain 
thickness  is  reached. 

When  this  occurs  the  attendant  removes  the  thick  sheet 
by  a  dexterous  movement  of  a  sharp  stick  across  the  face 
of  the  roll.  The  wet  pulp  at  this  stage  consists  of  30  per 
cent,  air-dry  pulp  and  70  per  cent,  of  water. 

Hydraulic  Pressing. — The  sheets  taken  from  the  wet 
press  machine  are  folded  into  a  convenient  shape  and  piled 
up,  coarse  pieces  of  sacking  being  placed  between  the  sheets. 
At  stated  intervals  the  piles  are  submitted  to  pressure  in 
hydraulic  presses  in  order  to  remove  further  quantities  of 
water,  which  slowly  drains  away  through  the  sacking.  In 
this  way  a  mass  of  pulp  in  the  form  of  thick  folded  sheets 
containing  50  per  cent,  of  dry  wood  pulp  is  produced. 

The  pieces  of  sacking  are  taken  out  and  the  sheets  put 
up  in  bales  of  any  required  weight,  usually  2  cwt.  or  4  cwt. 

The  Manufacture  of  Chemical  Wood  Pulp. 

Most  vegetable  fibres  are  converted  into  pulp  by  alkaline 
processes,  that  is  by  digesting  the  raw  material  with  caustic 
soda  and  similar  alkaline  substances.    Wood  may  be  treated 


WOOD  PULP  AND  WOOD  PULP  PAPERS 


105 


in  two  ways,  one  of  which  is  the  ordinary  soda  process,  and 
the  other  an  acid  treatment  requiring  the  use  of  sulphurous 
acid. 

Preparation  of  the  Wood. — The  logs  of  wood  are  cut  up 
and  barked  exactly  as  in  the  case  of  mechanical  pulp.  The 
short  two-foot  pieces  are  then  cut  up  into  small  flakes  about 
one  inch  square  and  half  an  inch  thick  by  means  of  a 
machine  known  as  a  clapper.  This  is  similar  in  construction 
to  a  barker,  consisting  of  a  heavy  iron  disc  rotating  at  a 
high  speed  inside  a  stout  cover.  The  disc  revolves  in  a 
vertical  position,  and  three  projecting  knives  slice  up  the 
logs  into  flakes.  For  this  purpose  the  disc  is  provided 
with  three  slots  which  radiate  from  the  centre  towards  the 
circumference  for  about  12  inches.  The  knives  can  be 
adjusted  so  that  they  stand  up  through  the  slots  and  above 
the  surface  of  the  disc  to  any  required  distance. 

In  order  to  ensure  uniformity  in  the  size  of  the  chips, 
the  practice  is  frequently  adopted  of  sifting  the  wood 
leaving  the  chipper.  The  sieve  is  a  large  skeleton  drum, 
the  outer  surface  of  which  is  made  of  a  coarse  wire  cloth 
capable  of  passing  all  pieces  of  the  size  mentioned.  Larger 
chips  and  pieces  are  retained  in  the  drum  as  it  revolves  in 
a  horizontal  position  and  only  fall  out  on  reaching  the 
extreme  end  of  the  machine. 

The  Digesters. — The  object  of  boiling  the  wood  under 
pressure  with  chemicals  is  to  dissociate  the  valuable  fibrous 
portion  of  the  plant  from  the  resinous  and  non-fibrous 
portion.  In  this  process  the  wood  loses  half  its  weight,  the 
yield  of  pulp  being  about  50  per  cent.,  and  the  remainder  is 
dissolved  out  by  the  chemical  solution.  The  conditions  of 
treatment  are  extremely  varied  in  character,  the  quality  of 
the  pulp  produced  varying  in  proportion. 

The  digesters  are  either  spherical,  cylindrical,  or  egg- 
shaped,  being  constructed  to  revolve  at  a  slow  rate  of  speed, 


106 


THE  MANUFACTURE  OF  PAPER 


Fig.  33. — Wood  Pulp  Digester,  partly 
ill  elevation,  partly  in  section. 


or  fixed  permanently  in 
an  upright  position. 
Spherical  boilers  are 
usually  9  or  10  feet  in 
diameter,  the  cyhndrical 
digesters  being  40  or  50 
feet  high  and  12  or  15 
feet  diameter,  the  larger 
ones  being  capable  of 
taking  20  tons  of  wood 
for  each  operation. 

For  the  alkaline  pro- 
cess the  interior  of  the 
digester  does  not  require 
any  special  treatment, 
but  with  the  acid  process 
the  internal  portion  of 
the  boiler  is  carefully 
lined  with  a  thick  layer 
of  acid  -  resisting  brick 
and  cement. 

The  contents  of  the 
digester  are  heated  by 
means  of  high-pressure 
steam,  which  is  blown 
direct  into  the  mass  or 
passed  through  a  coil 
lying  at  the  bottom  of 
the  vessel.  In  the 
former  case  the  steam  is 
condensed  by  the  liquor, 
the  volume  of  which  is 
consequently  increased, 
while  in  the  latter  case 


WOOD  PULP  AND  WOOD  PULP  PAPERS  107 


the  condensed  steam  is  drawn  off  continuously  from  the 
pipes.    Each  system  has  its  own  particular  advantages. 

Different  Kinds  of  Chemical  Wood  Palp. — According  to 
the  method  of  treatment  so  the  quality  of  the  pulp  varies. 
The  chemicals  used,  the  system  of  boiling,  the  temperature 
of  digestion,  the  strength  of  the  solutions,  the  duration  of 
the  cooking  period,  and,  last  but  not  least,  the  species  of 
wood,  are  all  determining  factors  in  the  value  of  the  ultimate 
product. 

Soda  Pulp. — This  is  prepared  by  digesting  w^ood  with 
caustic  soda  in  revolving  boilers  for  eight  or  ten  hours  at 
a  pressure  of  60  to  80  lbs. 

Sulphate  Pulp. — Prepared  by  digesting  the  wood  with 
a  mixture  of  caustic  soda,  sulphide  of  soda,  and  sulphate 
of  soda. 

S2dphite  Pulp. — The  process  most  generally  adopted  for 
the  manufacture  of  wood  pulp  is  the  treatment  of  the 
material  in  brick-lined  digesters  with  bisulphite  of  lime  for 
eight  to  nine  hours  at  a  pressure  of  80  lbs. 

Mitscherlich  Pidp. — This  is  sulphite  pulp  prepared  by 
digesting  the  wood  at  a  much  lower  temperature  and  for  a 
longer  period  than  the  ordinary  sulphite.  The  steam  is 
not  blown  direct  into  the  mass  of  wood,  and  the  pressure 
seldom  exceeds  45  or  50  lbs.,  the  time  of  boiling  occupying 
45  to  50  hours.    So  called  from  the  name  of  the  inventor. 

SLdphite  Wood  Pulp. — This  name  is  given  to  pulp  pre- 
pared by  digesting  wood  with  solutions  containing  sul- 
phurous acid,  or  salts  of  sulphurous  acid.  The  acid  is 
produced  by  burning  sulphur  or  certain  ores  containing 
sulphur,  such  as  copper  or  iron  pyrites,  in  special  ovens. 
The  most  modern  form  of  oven  consists  of  a  cylindrical  cast- 
iron  drum  revolving  slowly  in  a  horizontal  position  on 
suitable  bearings.  The  sulphur  is  thrown  at  intervals,  or 
fed  automatically,  into  the  oven,  the  amount  of  air  being 


108 


THE  MANUFACTURE  OF  PAPER 


carefully  regulated  to  avoid  the  formation  of  sulphuric  acid 
in  the  later  stages  of  preparation.  The  sulphur  is  also 
burnt  in  stationary  ovens  which  consist  of  flat  shallow 
closed  trays. 

The  hot  sulphurous  acid  gas  passes  through  pipes  and  is 
cooled,  after  which  it  is  brought  into  contact  with  water  and 


Fig.  34, — View  of  ordinary  Siilphur-burning  Ovens. 


lime  for  the  production  of  the  bisulphite  of  lime.  This  is 
accomplished  by  one  of  two  methods  as  follows. 

Tower  System. — The  cool  gas  is  drawn  into  high  towers 
usually  built  of  wood,  7  or  8  feet  diameter,  which  are 
filled  with  masses  of  limestone.  From  tanks  at  the  top  of 
each  tower  a  carefully  regulated  quantity  of  water  flows 
down  upon  the  limestone  and  absorbs  the  ascending  column 


WOOD  PULP  AND  WOOD  PULP  PAPERS 


109 


of  gas,  this  being  drawn  into  the  tower  from  the  bottom. 
The  hmestone  is  simultaneously  dissolved,  and  the  liquid 
which  flows  out  from  the  pipes  at  the  bottom  of  the  tower 
consists  of  lime  dissolved  in  sulphurous  acid,  together  with 
a  certain  proportion  of  free  sulphurous  acid.  This  is 
generally  known  as  a  solution  of  bisulphite  of  lime. 

Tank  System. — The  somewhat  costly  tower  system  has  in 
many  cases  been  superseded  by  the  use  of  a  number  of 
huge  wooden  vats,  10  to  12  feet  diameter  and  8  to  10  feet 
high.  These  tanks  are  filled  with  water  and  a  known 
quantity  of  slaked  lime.  The  gas  is  forced  into  the  tanks 
by  pressure  or  drawn  through  by  suction,  and  the  conver- 
sion of  the  milk  of  lime  into  bisulphite  of  lime  proceeds 
automatically.  In  order  to  ensure  complete  absorption  the 
gas  passes  through  the  tanks  in  series,  so  that  the  spent 
gases  leaving  the  vats  do  not  contain  any  appreciable 
amount  of  sulphurous  acid. 

In  order  to  obtain  pulp  of  uniform  quality  it  is  necessary 
that  the  liquor  should  be  of  constant  composition.  The 
formula  differs  in  the  various  mills  according  to  the  condi- 
tions which  are  found  most  suitable. 

Sulphite  Digesters. — The  almost  universal  form  of  boiler 
employed  in  cooking  wood  by  the  sulphite  process  is  a  tall 
cylindrical  vessel  of  about  50  feet  in  height,  and  14  to  15 
feet  internal  diameter,  lined  with  acid-resisting  brick. 

This  form  of  digester  is  capable  of  holding  20  tons  of 
wood  at  one  charge,  yielding  10  tons  of  finished  pulp. 

The  chipped  wood  is  discharged  into  the  digesters  from 
huge  bins  erected  just  above  the  openings  to  the  digesters, 
so  that  the  latter  can  be  filled  without  any  delay  and  the 
requisite  quantity  of  sulphite  liquor  added. 

The  manhole  or  cover  is  at  once  put  on,  securely  fastened, 
and  steam  turned  on  gradually  until  the  pressure  reaches 
70  or  80  lbs.,  at  which  pressure  the  cooking  is  steadily 


110 


THE  MANUFACTURE  OF  PAPER 


maintained.  The  progress  of  the  operation  is  watched  and 
samples  of  the  liquor  drawn  from  the  boiler  at  intervals  to 
be  tested,  so  that  the  boiling  may  be  stopped  when  the 
results  of  the  testing  show  the  wood  is  sufficiently  cooked. 

There  is  no  special  difficulty  in  this  operation,  provided 
the  necessary  conditions  are  observed.  It  is  important 
that  the  wood  should  be  dry,  and  that  the  proportion  of 
sulphite  liquor  per  ton  of  dry  wood  should  be  constant.  If 
the  wood  happens  to  be  wet,  due  allowance  must  be  made 
for  the  excess  water  and  a  somewhat  stronger  liquor  used 
in  order  to  compensate  for  this.  Other  precautions  of  a 
similar  character  are  observed  in  order  to  minimise  the 
danger  of  an  insufficiently  cooked  pulp. 

Washing. — When  the  pulp  has  been  boiled,  a  process 
which  generally  occupies  seven  or  eight  hours,  the  steam 
is  shut  off  and  the  contents  of  the  boiler  blown  out  into 
large  vats  known  as  blow-out  tanks,  the  pressure  of  steam 
remaining  in  the  digester  being  sufficient  to  empty  the 
softened  pulp  in  a  few  minutes.  Much  of  the  spent 
sulphite  liquor,  now  containing  the  dissolved  resinous  and 
non-fibrous  portions  of  the  original  wood,  drains  away  from 
the  mass  in  the  tank,  and  then  copious  supplies  of  clean 
water  are  added  in  order  to  wash  out  the  residual  liquors 
which  it  is  essential  to  remove. 

Numerous  other  devices  are  employed  to  ensure  the  com- 
plete washing  of  the  boiled  pulp. 

Screening. — The  production  of  a  high-class  pulp  necessi- 
tates proper  screening  to  eliminate  coarse  pieces  of  unboiled 
wood  and  the  knots,  the  latter  not  being  softened 
completely.  The  methods  adopted  vary  according  to 
requirements. 

For  uniform  clean  pulp  that  can  be  bleached  easily  the 
material  from  the  blow-out  tanks  is,  after  washing,  mixed 
with  large  quantities  of  water  and  run  through  sand  traps, 


WOOD  PULP  AND  WOOD  PULP  PAPERS 


111 


which  consist  of  long  shallow  wide  boxes  provided  with 
slanting  baffle-boards  to  retain  knots  and  large  pieces  of 
unsoftened  wood,  the  pulp  thus  partially  screened  being 
subsequently  treated  in  the  proper  screening  apparatus. 

Sometimes  the  washed  pulp  is  sent  direct  to  the  screens 
and  the  well-boiled  fibres  sorted  out  by  a  system  of  graded 
screens,  which  separate  the  completely  isolated  fibres  from 
the  bulk  and  retain  the  larger  pieces,  these  being  broken 
down  in  a  suitable  engine  and  put  back  on  the  screens. 

The  machinery  employed  for  screening  chemical  pulp  is 
identical  with  that  used  for  the  treatment  of  mechanical 
wood  pulp. 

Finisldng. — The  ordinary  sulphite  pulp  is  worked  up 
into  the  form  of  dry  sheets  for  the  market  and  not  sent  out 
in  a  wet  state  as  the  mechanical  wood.  There  are  several 
practical  disadvantages  in  preparing  the  latter  in  a  dry 
condition  which  do  not,  however,  occur  with  chemical 
pulp. 

Hence  the  pulp  after  being  screened  is  not  pressed  but 
submitted  to  a  different  process.  From  the  screens  the 
mixture  of  pulp  and  water,  the  latter  being  present  in  large 
quantity,  is  pumped  into  a  concentrator,  or  slusher,  as  it  is 
termed,  by  means  of  which  some  of  the  water  is  taken  out. 

The  slusher  consists  of  a  wooden  box  divided  into  two 
compartments  by  a  vertical  partition.  In  the  larger  compart- 
ment a  hollow  drum  covered  with  a  fine  wire  cloth  revolves, 
the  construction  and  purpose  of  which  are  precisely  the  same 
as  that  of  the  wet  press  machine  used  for  mechanical  pulp. 

As  the  drum  revolves  the  pulp  adheres  to  the  outer 
surface,  while  the  water  passes  through  the  wire  cloth. 
The  drum  is  not  completely  immersed  in  the  mixture,  so 
that  the  skin  of  pulp  is  brought  out  of  the  water  by  the 
rotation  of  the  drum.  When  this  takes  place  the  contact  of 
a  wooden  or  felt  covered  roll  which  revolves  on  the  top  of 


112 


THE  MANUFACTURE  OF  PAPER 


the  drum  causes  the  pulp  to  be  transferred  from  the  drum 
to  the  roll.  The  wet  pulp  is  contmuously  scraped  off  by  an 
iron  bar  or  doctor,  as  it  is  called,  resting  on  the  surface  of 
the  roll,  and  it  finally  drops  into  the  second  compartment 
of  the  slusher  in  a  more  concentrated  form  ready  for  the 
drying  machine. 

Drying. — The  mass  of  wet  pulp  from  the  slusher  is  con- 
veyed into  a  circular  reservoir  or  stuff  chest,  which  serves  to 
supply  the  machine  used  for  converting  the  pulp  into  dry 
sheets. 

The  machine  is  to  all  intents  and  purposes  a  Fourdrinier 
paper  machine,  and  the  process  is  similar  to  that  used  for 
the  manufacture  of  paper.  The  pulp  flows  in  a  continuous 
stream  on  to  a  horizontal  endless  wire,  which  carries  it 
forward  as  a  thin  layer;  the  water  drains  through  the 
meshes  of  the  wire,  further  quantities  being  removed  by 
suction  boxes,  which  draw  away  the  water  by  virtue  of  the 
vacuum  produced  by  special  pumps.  The  wet  sheet  then 
passes  between  the  couch  rolls  which  compress  the  pulp, 
squeezing  out  more  water,  and  then  through  jwess  rolls, 
which  finally  give  a  firm  adherent  sheet  of  pulp  containing 
70  per  cent,  of  water.  The  sheet  is  dried  by  passing  over 
a  number  of  steam  heated  cylinders,  which  cause  all  the 
moisture  to  evaporate  from  the  pulp.  At  the  end  of  the 
machine  the  dry  pulp  is  cut  up  into  sheets  of  any  con- 
venient size,  and  packed  up  in  bales  of  two  or  four  cwts. 

Mitscherlich  Sulphite  Pulp. — This  term  is  applied  to 
sulphite  wood  prepared  by  submitting  the  chipped  wood 
to  a  comparatively  low  pressure  for  a  long  period.  The 
wood  is  placed  in  the  stationary  upright  form  of  digester 
with  the  requisite  amount  of  liquor,  and  the  heating  pro- 
duced by  the  passage  of  steam  through  a  leaden  coil  lying 
at  the  bottom  of  the  digester,  so  that  the  steam  does  not 
condense  in  the  liquor  but  in  the  coil,  from  which  it  is 


WOOD  PULP  AND  WOOD  PULP  PAPERS 


113 


drawn  off.  The  pressure  seldom  exceeds  45  lbs.  but  the 
duration  of  the  cooking  is  thirty-six  to  forty-eight  hours. 
The  boiler  is  not  emptied  under  pressure,  but  the  pulp  is 
discharged  from  the  digester  after  the  pressure  has  been 
lowered,  and  the  manhole  taken  off.  The  contents  are 
usually  shovelled  out  by  the  workmen. 

The  pulp  is  carefully  washed,  screened  and  made  up  into 
wet  sheets  on  the  ordinary  wet  press  machine.  This  pulp 
is  never  dried  on  the  Fourdrinier  like  the  common  sulphite, 
as  its  special  qualities  can  only  be  preserved  by  the  treat- 
ment described.  This  pulp  is  particularly  suitable  for 
parchment  papers,  grease  proofs  and  transparent  papers. 

Soda  Wood  Pulp. — The  chipped  wood  is  boiled  in 
stationary  or  revolving  digesters  for  eight  or  nine  hours  at 
a  pressure  of  70  or  80  lbs.  A  solution  of  caustic  soda 
is  employed,  about  16  to  20  per  cent,  of  the  weight 
of  the  wood  being  added  to  the  contents  of  the  digester. 
Live  Bteam  is  blown  direct  into  the  mass,  and  after  the 
operation  the  spent  liquor  is  carefully  kept  for  subsequent 
treatment.  The  pulp  is  washed  in  such  a  manner  that  the 
amount  of  water  actually  used  is  kept  down  to  the  smallest 
possible  volume  consistent  with  a  complete  removal  of 
soluble  matters.  This  is  done  in  order  that  the  spent 
liquors  may  be  treated  for  the  recovery  of  the  soda. 

Recovery  of  Spent  Liquors. — When  wood  is  cooked  by  the 
soda  and  sulphate  processes  the  solutions  containing  the 
dissolved  organic  matter  from  the  wood  can  be  evaporated, 
and  the  original  chemical  recovered.  In  the  case  of  soda 
pulp  the  method  of  treatment  is  as  follows :  the  spent 
liquors  and  the  washings  are  evaporated  by  means  of  a 
multiple  effect  vacuum  apparatus  to  a  thick  syrup.  The 
concentrated  liquor  produced  is  then  burnt  in  special 
furnaces,  all  the  organic  matter  being  consumed,  leaving  a 
black  mass  which  consists  mainly  of  carbonate  of  soda. 

p.  I 


114 


THE  MANUFACTURE  OF  PAPER 


The  mass  is  washed  with  water  to  remove  the  carbonate 
which  is  afterwards  converted  into  caustic  soda  by  being 
boiled  with  lime. 

The  spent  liquors  from  the  sulphite  process  have  no 


Fig.  35. — Spruce  Wood  Pulp. 

value,  for  they  cannot  be  recovered  by  this  method.  At 
present  the  whole  of  the  sulphur  used  and  the  organic 
matter  dissolved  from  the  wood  is  lost.  This  means  the 
loss  of  about  250  to  350  lbs.  of  sulphur  and  nearly  50  per 
cent,  of  the  weight  of  wood  for  every  ton  of  pulp  produced. 


WOOD  PULP  AND  WOOD  PULP  PAPEES 


115 


Wood  Pulp  ;  Microscopic  Features. 

Mechanical  and  chemical  pulps  are  readily  distinguished 
under  the  microscope.    The  former  consists  of  fibres  of 


Fig.  36.— Mechanical  Wood  Pulp. 

irregular  shape  and  size,  mixed  with  a  large  proportion  of 
structureless  particles,  all  bearing  evidence  of  having  been 
torn  apart  and  separated  by  mechanical  methods.  The 
chemical  pulp,  on  the  other  hand,  consists  of  fibres  isolated 
by  a  process  which  preserves  them  in  perfect  condition  and 

I  2 


116 


THE  MANUFACTURE  OF  PAPER 


form.  The  pulp  from  the  various  woods  can  be  differentiated 
by  minute  details  in  fibre  structure,  some  of  the  woods  being 
determined  from  the  presence  of  characteristic  cells. 

The  use  of  aniline  sulphate  can  also  be  resorted  to,  and 
for  microscopic  work  the  most  useful  reagent  is  a  mixture 
of  zinc  chloride  and  iodine.  This  produces  an  intense 
yellow  colour  with  mechanical  pulp  and  a  bluish  colour 
with  sulj)hite  and  other  chemical  wood  pulps. 

The  Daily  Newspaper. 

The  newspapers  of  the  present  day  are  made  almost 
exclusively  of  wood  pulp.  The  use  of  the  latter  material 
for  paper-making  has  steadily  increased  from  the  date  of 
its  introduction  about  a.d.  1870,  when  wood  pulp  was 
imported  into  England  in  considerable  quantities. 

News  and  cheap  printings  consist  of  mechanical  and 
chemical  wood  pulps  mixed  in  varying  proportions  deter- 
mined chiefly  by  the  price  paid  for  the  finished  paper.  In 
some  cases  the  proportion  of  mechanical  wood  pulp  is  as 
much  as  85  per  cent.,  though  the  average  composition  of  a 
cheap  wood  paper  is  represented  by  the  following  propor- 
tions :  Mechanical  pulp,  70  per  cent. ;  sulphite  pulp,  20  per 
cent. ;  loading,  10  per  cent. 

Some  idea  of  the  enormous  quantity  of  material  used  for 
the  daily  press  may  be  judged  from  one  or  two  examples. 
A  certain  poj^ular  weekly  newspaper  having  a  circulation  of 
one  and  a  quarter  million  copies  per  week  requires  every 
week  137  tons  of  paper  produced  from  170  tons  of  wood. 
A  popular  halfpenny  newspaper  boasting  a  circulation  of 
about  one-half  million  copies  per  day  consumes  185  tons 
of  paper  manufactured  from  230  tons  of  wood,  every  week. 

It  is  easy  also  from  these  facts  to  estimate  the  amount 
of  timber  which  must  be  cut  down  to  supply  the  demand 
for  newspapers  and  cheap  printings. 


WOOD  PULP  AND  WOOD  PULP  PAPERS  117 

The  manufacture  of  news  calls  for  considerable  skill  and 
able  management,  owing  to  the  keen  competition  amongst 
the  paper  mills  devoted  to  this  class  of  paper.  The  process 
as  carried  on  in  England  is  as  follows  : — 

The  mechanical  pulp,  reaching  the  mill  in  the  form  of 
thick  sheets  suitably  packed  up  into  bales,  is  first  broken 
up  again  into  moist  pulp.  Various  machines  are  used  for 
this,  such  as  Wurster's  kneading  engine,  Cornett's  breaker, 
or  some  similar  contrivance.  An  old  potcher,  such  as  is 
used  for  the  breaking  and  washing  of  rags,  makes  a  good 
pulp  disintegrator.  The  broken  pulp  is  discharged  into 
beating  engines  in  any  suitable  or  convenient  manner  and 
the  right  proportion  of  chemical  wood  pulp  added  in  the 
form  of  dry  sheets.  The  beating  process  only  occupies 
thirty  to  forty  minutes  in  the  case  of  the  common  news, 
a  marked  contrast  to  the  eight  or  nine  hours  required  by 
rags.  China  clay  is  added  to  the  contents  of  the  beater, 
ten  to  twelve  per  cent,  being  the  general  practice.  This  is 
followed  by  a  measured  quantity  of  rosin  size,  and  after 
thorough  incorporation  the  size  is  precipitated  upon  the 
fibres  by  means  of  alum. 

In  the  commoner  qualities  of  these  papers  the  materials 
are  added  in  the  dry  state,  but  for  finer  grades  of  news- 
paper the  china  clay  is  mixed  with  water,  and  carefully 
drained  through  a  fine  sieve  before  use.  The  alum  cake  is  also 
dissolved  and  treated  in  a  similar  manner  in  order  to  keep  out 
dirt  and  coarse  particles  likely  to  produce  holes  in  the  paper. 

The  paper  machine  used  for  the  manufacture  of  cheap 
printings  is  constructed  to  produce  as  much  as  100  to  180 
tons  of  finished  paper  per  week,  every  detail  being  arranged 
for  a  large  output  at  a  very  high  speed.  In  the  modern 
machine  it  is  possible  to  produce  paper  at  the  rate  of 
450  to  550  feet  per  minute,  the  width  of  the  sheet  being  from 
120  to  160  inches. 


118 


THE  MANUFACTURE  OF  PAPER 


Careful  attention  is  paid  to  economy  of  every  kind  with 
regard  to  the  power  required  for  driving  the  machine,  the 
amount  of  steam  consumed  in  di-ying  the  paper,  recovery 
of  excess  of  fibre  and  china  clay  which  escapes  from  the 
machine  wire,  and  similar  details  of  a  mechanical  order. 


Fig.  37. — The  Screens  for  removiDg  Coarse  Fibres  from  Beaten 

Pulp. 


The  beaten  pulp,  after  being  sized  and  coloured,  is 
discharged  into  huge  circular  brick  tanks,  or  stuff  chests, 
two  of  which  are  found  with  each  paper  machine.  The 
supply  of  pulp  and  water  for  the  machine  is  taken  from 
one  stuff  chest  while  the"second  is  being  fihed  up  from  the 


120 


THE  MANUFACTUEE  OF  PAPER 


beating  engines,  in  order  to  secure  a  mixture  of  constant 
composition. 

The  pulp  is  pumped  from  the  stuff  chest  into  a  small 
regulating  box  placed  above  the  machine  wire,  and  this  box 
is  kept  full  of  beaten  pulp  so  that  the  supply  of  pulp  and 
water  to  the  machine  is  perfectly  constant.  The  pulp, 
diluted  with  the  proper  quantity  of  hack -water,  is  carefully 
strained  through  rotary  screens  and  allowed  to  flow  through 
a  distributing  box  on  to  the  machine  wire,  where  it  rarpidly 
forms  a  sheet  of  paper. 

The  excess  of  water,  together  with  a  certain  proportion 
of  fine  fibre  and  china  clay,  falls  through  the  wire,  and  is 
caught  below  in  a  shallow  box,  called  the  save-all.  This 
hack-icater,  as  it  is  called,  is  used  over  again  for  diluting 
the  beaten  pulp  to  the  right  consistency,  as  already 
described. 

The  whole  of  the  water  obtained  in  this  way  is  not  all 
utilised  in  the  regulating  box,  and  any  surplus  is  pumped 
up  continually  into  large  store  tanks  and  used  in  the 
beating  engines  for  breaking  down  the  dry  pulp. 

In  many  cases,  where  a  large  quantity  of  water  is  used 
on  the  machine,  special  methods  have  to  be  adopted  for  the 
recovery  of  all  the  fibre  and  clay,  which  would  otherwise 
be  lost,  and  there  are  many  ingenious  systems  in  use 
whereby  this  saving  is  effected. 

The  most  usual  practice  is  to  allow  the  excess  of  water, 
which  contains  from  8  to  15  lbs.  of  suspended  matter  per 
thousand  gallons,  to  flow  through  a  series  of  brick  tanks  at 
a  slow  rate  of  speed.  The  clay  and  fibre  settle  to  the 
bottom  of  the  tanks,  and  the  water  passes  away  from  the 
last  tank  almost  clear  and  free  from  fibre  and  loading. 

The  drying  of  the  moist  paper  leaving  the  press  rolls  of 
the  machine  is  effected  in  the  usual  manner  by  means 
of  drying  cylinders.    On  account  of  the  great  increase  of 


WOOD  PULP  AND  WOOD  PULP  PAPERS  P21 


speed  at  which  the  paper  is  produced,  the  number  of  dry- 
ing cyhnders  has  also  been  increased,  and  at  the  present 
time  a  machine  of  this  description  is  provided  with  28  or 
32  cyhnders,  the  object  being  to  dry  the  paper  economically. 

Mechanical  Wood  Pulp  in  Paper. 

The  presence  of  mechanical  wood  pulp  in  paper  is 
detected  by  means  of  several  reagents,  which  produce  a 
definite  colour  when  applied  to  a  sheet  of  paper  containing 
mechanical  wood.  The  depth  of  colour  obtained  indicates 
approximately  the  percentage  present,  but  considerable 
practice  and  experience  is  necessary  to  interpret  the  colour 
exactly.  A  more  rehable  method  of  estimating  the  per- 
centage of  mechanical  wood  in  a  paper  is  by  microscopic 
examination. 

The  reagents  which  can  be  used  are — 

(1)  Nitric  Acid. — This  produces  a  brown  stain  on  the 
paper,  but  it  is  not  a  desirable  reagent  for  ordinary  office 
purposes. 

(2)  A)iiline  Sulphate. — A  solution  of  this  is  prepared  by 
dissolving  5  parts  of  aniline  sulphate  in  100  parts  of  dis- 
tilled water.  When  applied  to  the  surface  of  news  a  yellow 
coloration  is  produced,  more  or  less  intense  according  to 
the  amount  of  mechanical  wood  present.  It  can  only  be 
used  with  white  papers,  or  pa^jers  very  slightly  toned. 

(3)  Pliloroglucine. — This  sensitive  reagent,  which  gives 
a  rose-pink  colour  when  brushed  on  to  the  surface  of  the 
paper,  is  prepared  by  dissolving  4  grammes  of  phloro- 
glucine  in  100  c.c.  of  rectified  spirits,  and  adding  to  the 
mixture  50  c.c.  of  pure  concentrated  hydrochloric  acid. 

There  are  several  other  aniline  compounds  which  give 
colour  reactions  of  a  similar  character,  but  they  are  not 
often  used.    The  phloroglucine  reagent  fails  as  a  test  for 


122 


THE  MANUFACTURE  OF  PAPER 


mechanical  wood  in  papers  which  have  been  dyed  with 
certain  aniline  colours,  for  example,  metanil  yellow. 
Paper  which  has  been  coloured  with  this  dye  will,  when 
moistened  with  the  phloroglucine  reagent,  give  an  intense 
pink  colour,  even  if  no  mechanical  wood  is  present.  This 
is  due  to  the  fact  that  the  dye  itself  is  acted  upon  by  the 
hydrochloric  acid  in  the  test  reagent.  The  same  colour  is 
produced  on  the  paper  with  hydrochloric  acid  se. 

There  is  little  difficulty  in  distinguishing  between  the 
colour  arising  from  the  presence  of  such  a  dye,  because 
the  effect  is  instantaneous,  whereas  the  coloration  due 
to  mechanical  wood  develops  gradually.  Moreover,  the 
reaction  due  to  the  presence  of  metanil  yellow  gives  a 
perfectly  even  coloured  surface,  whereas  with  mechanical 
wood  pulp  the  fibres  appear  to  be  more  deeply  stained  than 
the  body  of  the  paper. 

Output  of  a  Paper  Machine. — The  quantity  of  paper 
which  can  be  produced  on  the  paper  machine  is  readily 
calculated  from  the  following  data  : — 

Speed  of  machine  in  feet  per  minute  F 

Nett  deckle  width  in  inches  D 

Width  of  sheet  of  paper  in  inches  W 

Length  of  sheet  of  paper  in  inches  L 

Number  of  sheets  in  ream  S 

Weight  of  paper  per  ream  R 

The  general  formula  for  the  output  of  paper  per  hour  is 

Output  m  lbs.  per  hour  =  =  tft —  . 

^  ^  S  X  L  X  W 

When  the  number  of  sheets  in  the  ream  is  480,  this 
formula  simplifies  to 

,            li  X  R  X  F  X  D 
Output  m  lbs.  per  hour  =  ~  f  • 

X    r  V 

The  term  "  nett  deckle  width  "  applies  to  the  width  of 


WOOD  PULP  AND  WOOD  PULP  PAPEES  123 


124 


THE  MANUFACTUEE  OF  PAPEE 


the  trimmed  finished  paper  at  the  end  of  the  machine. 
The  formula  takes  no  account  of  the  allowance  required  for 
trimming  edges.  In  most  cases  the  deckle  width  of  the 
machine  is  arranged  so  that  the  paper  is  cut  into  strips  of 
equal  width  when  leaving  the  calenders,  e.g.,  a  deckle  of 
80  inches  will  give  4  sheets,  each  20  inches  wide. 

The  method  by  which  the  general  formula  is  obtained 
may  be  explained  by  an  example. 

What  is  the  output  of  a  machine  having  a  speed  of 
100  feet  per  minute,  with  an  80-inch  deckle,  producing  a 
sheet  of  paper  20  inches  by  30  inches,  weighing  30  lbs.  per 
ream  of  480  sheets  ? 

The  machine  produces  every  minute  a  sheet  of  paper 
100  feet  long  and  80  inches  wide. 

Hence  output  per  minute  in  square  inches 
=1  12  X  100  X  80. 
Output  per  hour  in  square  inches 
=  60  X  12  X  100  X  80. 

Now  each  (20  x  30  X  480)  square  inches  is  area  of 
one  ream. 

Output  of  paper  per  hour  in  reams 

V  _  60  X  12  X  100  X  80 
~      480  X  30  X  20  • 
Output  of  paper  per  hour  in  lbs. 

_  720  X  100  X  80  X  30 

480  X  30  X  20 
=  600  lbs. 

The  general  formula  may  be  applied  for  the  purpose 
of  calculating  the  speed  at  which  the  machine  must  be 
driven. 

Example. — A  machine  with  75-inch  deckle  is  required  to 
produce  6  cwts.  per  hour  of  a  paper  25  inches  by  18  inches 


WOOD  PULP  AND  WOOD  PULP  PAPEES  125 


(500  sheets),  weighing  19  lbs.  to  the  ream.    At  what  speed 
is  the  machine  to  be  driven  ? 
Output  in  lbs.  per  hour 

^  720  X  F  X  D  X  R 
~       S  X  L  X  W 

_  720  X      X  75  X  19 
"      500  X  18  X  25 

F  =  148  feet  per  minute. 


CHAPTER  YI 


BROWN  PAPERS  AND  BOARDS 


Common  Brow7is. — The  raw  material  used  in  the  manu- 
facture of  common  brown  papers  is  chiefly  jute  and  waste 
fibres  of  every  description,  such  as  waste  cuttings  from 
boxboard  factories,  old  papers,  wood  pulp  refuse,  and  other 
substances  of  a  like  nature.  The  jute,  in  the  form  of  sack- 
ing or  old  gunny  bags,  and  the  hemp  refuse,  in  the  shape 
of  old  rope  and  string,  are  subjected  to  a  slight  chemical 
treatment  just  sufficient  to  isolate  the  fibres  to  a  condition 
in  which  it  is  possible  to  work  them  up  into  paper.  The 
bagging  and  string  are  cut  up  in  a  rag  chojDper  and  boiled 
in  revolving  boilers  with  lime  or  caustic  soda  for  several 
hours  at  a  pressure  of  20 — 30  lbs.,  the  lime  being  used  when 
it  is  desired  to  manufacture  a  harsh  paper,  and  the  caustic 
soda  being  employed  for  the  production  of  paper  having  a 
softer  feel.  Tbe  pulp  is  not  always  washed  very  com- 
pletely after  the  process  of  digestion,  as  is  the  case  with 
white  papers,  and  it  is  often  possible  to  extract  from  brown 
papers  of  this  class  a  considerable  proportion  of  the  alka- 
line matter  which  has  not  been  thoroughly  removed  from 
the  boiled  pulp.  The  presence  of  this  alkaline  residue  does 
not  affect  the  quality  of  ordinary  brown  paper,  but  is 
frequently  a  serious  defect  in  the  case  of  middles  or  straw 
boards,  which  are  afterwards  utilised  for  boxes  and  covered 
with  coloured  papers.  The  colour  of  the  paper  pasted  on 
to  such  incompletely  washed  boards  is  frequently  spoilt  by 
the  action  of  the  alkali  when  moistened  with  the  paste 


BROWN  PAPERS  AND  BOARDS 


127 


used,  many  aniline  dyes  being  susceptible  to  the  small 
proportion  of  alkali  present. 

The  stronger  materials,  such  as  jute  or  old  rope  and  string, 
are  either  used  by  themselves  or  blended  with  inferior  raw 
material  according  to  the  quality  of  the  paper  being  made. 
The  jute  and  hemp  fibres  are  generally  beaten  by  themselves 
in  the  engine  before  the  other  materials  are  added.  The 
pulp  is  mixed  with  the  required  amount  of  loading,  while 
the  sizing  and  colouring  operations  are  carried  out  in  the 
usual  way. 

The  common  brown  papers  are  known  by  a  variety  of 
trade  names  which  at  one  time  indicated  the  nature  of  the 
fibrous  constituent,  but  at  the  present  day  the  name  is  no 
guide  or  indication  of  the  material  used  for  the  manufacture 
of  the  paper.  The  common  heavy  brown  used  for  wrapping 
sugar  and  sundry  groceries  made  in  heavy  grey  and  blue 
shades  is  a  coarse  paper  made  from  cheap  materials  and 
containing  a  large  proportion  of  mineral  matter.  It  is 
usually  supplied  under  the  trade  name  of  royal. 

A  somewhat  lighter  and  stronger  wrapping  paper  of  a 
white  or  buff  colour,  used  for  wrapping  groceries,  tea,  and 
cotton  goods,  is  that  known  as  casings,  a  name  probably 
derived  from  the  application  of  this  paper  originally  to  the 
lining  of  cases. 

Manila  papers  so  called  were  originally  made  from 
rope,  but  the  term  is  now  applied  to  papers  which  may  be 
made  entirely  of  wood  pulp. 

Rope  browns  are  common  papers  made  of  fairly  strong 
material  of  a  miscellaneous  character,  this  name  having 
been  derived  from  the  fact  that  rope  and  similar  fibre  were 
at  one  time  used  exclusively. 

Wood  Palp  Wrappers. — Most  of  the  papers  of  the  present 
day  are  made  from  wood  pulp,  this  material  giving  a  thin, 
light,  tough  paper,  which  is  pleasant  to  handle  and  forms  a 


128 


THE  MANUFACTUEE  OF  PAPEE 


great  contrast  to  the  dense,  opaque,  heavily  loaded,  and 
inartistic  specimens  produced  some  years  ago.  Paper  of 
this  kind,  though  apparently  more  expensive  than  common 
browns,  is  really  more  economical  in  use.  The  paper  is  not 
only  stronger,  but  it  is  possible  to  obtain  a  larger  number 
of  sheets  for  a  given  weight.  The  great  advantage  in  the 
improvement  of  brown  papers  dates  from  the  introduction 
of  the  now  well-known  kraft  papers,  which  are  of  compara- 
tively recent  origin. 

Kraft  Paper. — The  term  Kraft,  meaning  "  strength,"  is 
applied  to  a  remarkably  strong  cellulose  paper  prepared  from 
spruce  and  other  coniferous  woods  by  the  soda  treatment, 
the  special  feature  of  the  process  being  an  incomplete 
digestion  of  the  wood. 

The  wood  previously  chipped  into  pieces  1  inch  to 
inches  in  length,  is  boiled  with  caustic  soda,  the  digestion 
being  stopped  before  the  wood  pulp  has  been  quite  softened, 
and  while  the  pulp  is  still  too  hard  to  be  broken  up  into 
isolated  fibres  by  simple  agitation  in  water.  The  pulp  after 
thorough  washing  is  disintegrated  by  means  of  an  edge- 
runner,  or  some  form  of  breaking  engine,  the  first  mentioned 
probably  giving  the  most  satisfactory  results,  and  converted 
into  paper  by  the  usual  methods. 

The  wood  can  also  be  reduced  by  the  sulphate  process,  in 
which  case  the  chipped  wood  is  boiled  in  a  liquor  to  which 
about  25  per  cent,  of  spent  lye  from  a  previous  cooking  is 
added. 

The  best  results  are  obtained  by  attention  to  the  cooking 
process  to  ensure  an  under-cooked  pulp,  by  careful  isolation 
of  the  fibres  in  a  kollergang,  or  edge-runner,  which  machine 
is  capable  of  separating  the  fibres  without  shortening  them, 
and  by  proper  manipulation  on  the  paper  machine. 

The  paper  produced  under  favourable  conditions  in  this 
direction  is  wonderfully  tough  and  strong  and  may  be 


BEOWN  PAPEES  AND  BOAEDS 


129 


quoted  as  the  most  recent  example  of  the  fact  that  the 
latent  possibilities  of  wood  pulp  have  by  no  means  been 
exhausted  or  even  thoroughly  investigated. 

Imitation  Kraft  Paper. — If  wood  is  boiled  in  water  at 
high  temperatures  the  fibre  is  softened  and  much  of  the 
resinous  matter  is  removed.  Such  wood,  if  ground  in  the 
same  way  and  by  the  same  methods  as  ordinary  mechanical 
wood  pulp,  is  readily  disintegrated,  and  a  long-fibred  pulp 
may  be  obtained.  The  process  of  boiling  short  2  feet  logs 
of  wood  in  a  digester  under  a  pressure  of  20 — 50  lbs.  has 
long  been  known.  The  wood  after  boiling  is  partly  washed 
and  then  worked  up  into  pulp  by  the  usual  mechanical 
process.  The  wood  is  easily  ground  and  yields  pulp  con- 
taining long  fibres  which  in  their  physical  properties 
closely  resemble  those  of  pure  wood  cellulose,  but  the 
original  constituents  of  the  wood  are  present  almost 
unchanged,  just  as  in  mechanical  pulp.  The  product 
obtained  by  grinding  is  a  very  tough  flexible  material  of  a 
brownish  yellow  colour,  and  the  paper  is  known  as  Nature 
hroivn.  It  is  chiefly  used  for  the  preparation  of  tough 
packing  papers,  for  the  covers  of  cheap  pocket-books,  and 
other  miscellaneous  purposes.  When  this  brown  mechanical 
wood  pulp  paper  is  glazed  on  both  sides  it  is  then  known  as 
ochre  glazed,  the  word  ochre  referring  to  the  colour.  When 
made  up  into  light  weight  papers  it  is  sold  as  imitation 
Jcraft  paper. 

A  great  variety  of  wrapping  papers  are  now  made  from 
wood  pulp,  such  as  sealings,  sulphite  browns,  manilas,  sulphite 
caps,  but  the  distinctions  between  these  papers  relate  chiefly 
to  the  amount  of  finish,  the  colour  and  size  of  the  sheet. 
The  methods  of  manufacture  only  differ  in  small  details  as 
indicated  by  these  distinctions. 

Fine  Wrappings. — The  papers  used  for  packing  small 
goods  such  as  silver  ware  and  other  delicate  articles  are 

p.  ^  K 


130 


THE  MANUFACTURE  OF  PAPEE 


generally  tissues,  the  better  qualities  of  which  are  made 
from  rag,  and  the  cheaper  qualities  from  wood  pulp. 
These  papers  are  known  as  tissue,  crepe,  crinkled  tissue, 
manila  tissue,  and  by  a  variety  of  trade  terms. 


Fig.  40. — Single  Cylinder  or  Yankee  Machine. 

Many  of  the  fine  wrappings  of  the  tissue  class  and  the 
somewhat  heavier  papers  known  as  M.  G.  Caps  are  manu- 
factured on  the  single  cylinder  machine,  which  produces  a 
paper  having  a  highly  polished  surface  on  one  side  and  a 
rough  unglazed  surface  on  the  other  side. 

In  the  single  cylinder  machine  the  beaten  pulp  passes 


BEOWN  PAPEES  AND  BOAEDS 


131 


from  the  stiiff-cbest  on  to  the  wh'e  of  the  ordinary  Four- 
drinier  machine  and  through  the  press  rolls,  but  instead  of 
being  dried  over  a  number  of  cylinders  the  paper  is  led 
over  one  single  cylinder  of  very  large  diameter  which  is 
heated  internally  with  steam.  The  paper  is  usually  pressed 
against  the  surface  of  the  cylinder  by  means  of  a  heavy 
felt,  which  is,  however,  sometimes  omitted.    The  side  of  the 


Fig.  41. — Section  of  Wet  Press,  or  Board  Machine. 


paper  coming  into  contact  with  the  cylinder  becomes  highly 
poHshed,  the  surface  in  contact  with  the  felt  remaining  in 
an  unfinished  rough  condition.  Tbis  paper  is  said  to  be 
machine  glazed  and  is  known  as  an  M.  G.  paper. 

Boards— Curds,  millboards,  middles,  boxboards,  carriage 
panels,  and  similar  paper  products  are  manufactured  either 
on  a  single  hoard  machiiw,  by  means  of  which  single 
sheets  of  any  required  thickness  can  be  obtained,  or  on  a 

K  2 


132 


THE  MANUFACTUEE  OF  PAPER 


continuous  hoard  maclime,  which  is  capable  of  producing 
cards  and  plain  or  duplex  boards  of  moderate  thickness. 

The  raw  material  used  consists,  as  in  the  case  of  browns 
and  wrappers,  of  every  conceivable  fibrous  substance  mixed 
with  mineral  matter  and  then  suitably  coloured.  The 
preliminary  processes  for  the  treatment  of  the  pulp  are 
exactly  the  same  as  those  employed  in  the  case  of  brown 
papers  up  to  the  point  at  which  the  beating  has  been  effected. 

Single  Board  Machine. 

The  beaten  pulp,  diluted  with  large  quantities  of  water, 
is  pumped  continuously  into  a  large  wooden  vat  of  rect- 
angular shape.  Inside  this  vat  revolves  slowly  a  hollow 
cylindrical  drum,  the  circumference  of  which  is  covered 
with  wire  gauze  of  fine  mesh.  The  drum  is  not  completely 
immersed  in  the  mixture  of  pulp  and  water,  so  that  as  it 
revolves  the  water  passes  through  the  wire,  while  the  pulp 
adheres  to  the  surface.  The  water  flows  regularly  into  the 
interior  of  the  drum  and  runs  away  through  pipes  fitted  at 
each  side  of  the  vat  near  the  axis  of  the  drum,  and  the  pulp 
is  brought  up  out  of  the  w^ater  until  it  comes  into  contact 
with  a  travelling  felt.  The  thin  moist  sheet  of  pulp 
adheres  to  this^  felt,  passes  through  squeezing  rolls  which 
remove  part  of  the  water,  and  is  finally  carried  between  two 
w^ooden  or  iron  rollers  of  large  diameter.  The  pulp  adheres 
to,  and  is  wound  up  on  the  upper  roller,  the  felt  being 
carried  back  by  the  lower  roller  to  the  vat.  When  the 
sheet  on  the  upper  roller  has  attained  the  desired  thick- 
ness, it  is  immediately  cut  off  and  transferred  to  a  pile  of 
similar  sheets,  a  piece  of  coarse  sacking  or  canvas  being 
interposed  between  every  wet  board.  The  dimensions  of  the 
full-sized  board  are  determined  by  the  diameter  of  the  upper 
roller  and  its  length.  A  roll  74  inches  wide  and  14  inches 
diameter  will  give  a  board  74  inches  by  44  inches. 


BROWN  PAPERS  ANi)  BOARDS 


133 


As  soon  as  a  sufficient  number  of  wet  boards  has  been 
obtained  they  are  submitted  to  pressure  in  order  to  remove 
the  excess  of  water  and  at  the  same  time  compress  the 
material  into  dense  heavy  boards.  The  pieces  of  sacking 
are  then  taken  out  and  the  boards  dried  by  exposure  to  air 
at  the  ordinary  temperature  or  in  a  heated  chamber. 


Fig.  42.— Double  Cylinder  Board  Machine. 


The  dried  boards  are  finished  off  by  glazing  rolls.  These 
rolls  compress  the  boards  still  further  and  impart  a  polished 
surface.  The  amount  of  ''finish  "may  be  varied  by  the 
pressure,  number  of  rollings,  temperature  of  the  rolls,  and 
by  damping  the  surface  of  the  dry  boards  just  before  they 
are  glazed.  The  boards  are  cut  to  standard  sizes  before  or 
after  glazing. 


134 


THE  MANUFACTUEE  OF  PAPER 


Duplex  Boards.~li  the  single  board  machine  is  fitted 
with  two  vats  instead  of  one,  it  is  possible  to  manufacture  a 
board  with  different  coloured  surfaces.  A  board  coloured 
red  on  one  side  and  white  on  the  other  is  manufactured  by 
having  one  vat  full  of  pulp  coloured  red  and  the  second  vat 
full  of  white  pulp.  The  thin  moist  sheets  from  the  two 
vats  are  brought  together  and  passed  through  the  glazing 
rolls,  which  cause  the  moist  sheets  to  adhere  closely  to  one 
another,  the  double  sheet  of  pulp  so  formed  being  wound  up 
on  the  rollers  at  the  end  of  the  machine.  The  board  is  then 
dried,  glazed,  and  finished  in  the  usual  way. 

The  same  principle  is  occasionally  adopted  on  the 
Fourdrinier  machine  for  duplex  wrappers.  Thus  a 
common  brown  pulp  is  worked  up  in  conjunction  with 
a  dyed  pulp  to  produce  a  brown  paper  having  one  surface 
of  good  paper  suitably  coloured.  The  brown  pulp  fiows  on 
to  the  wire  of  the  paper  machine,  and  after  it  has  been 
deprived  of  part  of  the  water  at  the  suction  boxes,  a  thin 
stream  of  coloured  pulp,  diluted  to  a  proper  consistency, 
flows  from  a  shallow  trough,  placed  across  and  above  the 
wire,  on  to  the  wet  brown  web  of  paper  in  such  a  manner 
as  to  completely  cover  it  as  a  thin  even  sheet  of  coloured 
pulp.  The  adhesion  of  the  latter  to  the  surface  of  the 
brown  paper  is  practically  perfect,  and  the  weight  of  the 
couch  and  press  rolls  ensures  uniform  felting  of  the  fibres. 

Middles. — This  term  is  applied  to  a  thin  or  thick  card- 
board made  of  common  material,  the  colour  and  appearance 
of  which  is  of  little  importance  for  inferior  goods. 
Boards  of  this  kind  are  covered  subsequently  with  papers 
of  all  colours  and  qualities,  and  the  origin  of  the  word 
"  middle  "  is  easily  seen.  The  manufacture  of  a  board 
consisting  of  two  outside  papers  of  good  material  and  a 
middle  produced  from  common  stuff  is  effected  by  the 
continuous  boxboard  machine,  unless  the  board  is  too 


BEOWN  PAPEES  AND  BOAEDS 


135 


thick  to  be  passed  over  drying  cylinders,  calendered,  and 
reeled,  in  which  case  the  boards  are  produced  on  an 
ordinary  wet  machine  and  the  paper  pasted  on  the  surface 
of  the  dry  board. 

The  term  is,  however,  now  also  applied  to  a  common 
IDaper  made  of  mechanical  wood  pulp  with  perhaps  a  little 
chemical  pulp,  used  for  tram  tickets,  cheap  advertising 
circulars,  common  calendar  cards,  and  similar  purposes, 
to  which  no  outer  surface  of  a  special  character  is  added. 

Continuous  Board  Machine. 

This  machine  differs  from  the  single  board  machine  in 
that  the  finished  board  can  be  produced  from  the  pulp  at 
one  operation.  It  is  used  principally  for  cards  and  boards 
of  moderate  thickness  which  can  be  wound  up  in  the  form 
of  a  reel  at  the  end  of  the  machine. 

The  mixture  of  pulp  and  water  is  pumped  into  two  or 
more  vats  and  formed  into  a  number  of  thin  sheets,  which 
are  all  brought  together  between  squeezing  rolls  and  passed 
through  heavy  press  rolls  which  compress  the  several 
layers  into  a  compact  mass.  The  thick  sheet  obtained  is 
dried  over  steam-heated  cylinders  which  are  placed  at  the 
end  of  the  press  rolls,  and  calendered.  The  whole  process, 
indeed,  resembles  that  of  ordinary  paper-making,  the  main 
difference  being  the  method  of  producing  the  wet  sheet  or 
card. 

Some  machines  are  constructed  with  six  or  seven  vats 
and  forty  to  fifty  drying  cylinders,  and  are  capable  of 
turning  out  a  large  quantity  of  finished  material. 

The  board  can  be  made  of  uniform  quality  and  texture 
throughout,  or  be  finished  off  with  high-grade  paper  on  one 
or  both  sides.  In  the  latter  case  the  constituents  of  the 
''middle"  part  are  waste  papers  and  raw  material  of 
inferior  quality,  the  outer  surface  of  wood  pulp,  white  or 


136 


THE  MANUFACTURE  OF  PAPER 


coloured  according  to  circumstances.  The  variety  of  papers 
and  boards  which  can  be  produced  is  due  to  the  fact  that 
the  several  vats  of  pulp  are  independent  of  one  another  and 
can  be  filled  with  any  kind  of  paper  stock.  The  combined 
sheets  forming  the  ultimate  board  are  dried  on  the  ordinary 
cylinders,  calendered,  and  reeled  up  at  the  end  of  the 
machine. 


CHAPTEK  VII 


SPECIAL  KINDS  OF  PAPER 

There  are  many  varieties  of  paper  products  obtained  by 
submitting  finished  paper  to  a  number  of  special  pro- 
cesses. Of  these  only  a  few  of  the  more  important  will 
be  described. 

These  products  can  be  divided  approximately  into  three 
classes  : — 

(1)  Papers  coated  on  one  side  or  both  sides  with  various 
substances,  such  as  "  art,"  photographic  papers,  etc. 

(2)  Papers  impregnated  with  chemicals,  such  as  blue 
print,  medicated,  and  cheque  papers. 

(3)  Paper  pulp  converted  into  modified  products  by 
chemical  treatment,  such  as  vulcanised  board,  viscoid,  etc. 

Of  the  first  class,  the  coated  papers  used  for  art  and 
chromo  illustrations  are  the  most  important. 

Of  the  second  class,  the  blue  prints  and  papers  impreg- 
nated with  chemicals,  chiefly  employed  for  the  production 
of  engineers'  drawings,  may  be  regarded  as  typical. 

In  the  third  class,  vegetable  parchment  and  vulcanised 
board  are  the  most  familiar. 

Parchment  Paper. — This  is  produced  by  the  action  of 
sulphuric  acid  uj^on  ordinary  paper,  the  most  suitable  for 
this  purpose  being  made  from  unsized  cotton  rag,  free 
from  such  additions  as  mechanical  wood  pulp.  The 
presence  of  the  latter  substance  should  be  avoided,  as  it 
is  lia,ble  to  char  or  burn,  so  that  in  the  finished  product  it 


138 


THE  MANUFACTURE  OF  PAPER 


shows  itself  in  the  form  of  small  holes.  The  process 
depends  upon  the  power  of  sulphuric  acid  to  change  the 
surface  of  the  paper  into  a  gelatinous  mass,  which  has 
been  shown  to  consist  of  a  substance  called  amyloid. 

The  best  parchment  is  made  from  pure  cellulose  such  as 
rag  or  chemical  wood  pulp.  The  quality  of  the  parchment 
depends  upon  attention  to  the  strength  of  the  acid,  the 
temperature  of  the  acid  bath,  the  period  of  immersion, 
the  complete  removal  of  the  acid,  and  the  careful  drying  of 
the  wet  parchment. 

The  acid  is  employed  at  a  strength  of  1*71  specific 


Fig.  43. — Apparatus  for  making  Parchment  Paper. 


gravity,  being  prepared  by  diluting  the  commercial  con- 
centrated acid  in  a  leaden  vessel,  with  a  sufficient  quantity 
of  water. 

The  parchment  is  generally  jDrepared  by  passing  a 
continuous  sheet  of  paper  through  a  bath  of  acid  of  the 
proper  strength  at  a  speed  which  ensures  the  correct 
period  of  immersion.  As  the  treated  paper  leaves  the 
bath  it  passes  through  squeezing  rolls  which  remove  the 
excess  of  acid,  and  the  jDaper  is  then  led  through  a  series 
of  tanks  containing  fresh  water,  the  last  traces  of  acid 
being  neutralised  by  small  additions  of  ammonia,  or  some 
alkali,  to  the  last  washing  tank.  The  wet  parchment  is 
then  passed  through  suitable  rollers  and  carefully  dried 
over  cylinders  heated  internally  by  steam.  The  paper  is 
kept  perfectly  stretched  as  it  dries,  because  it  shrinks 


SPECIAL  KINDS  OF  rAPER 


139 


enormously,  and  would  otherwise  become  cockled  and 
uneven. 

Thick  sheets  of  parchment  paper  are  frequently  made 
by  passing  three  sheets  of  paper  through  the  acid  bath  and 
bringing  them  together  between  the  rollers  before  washing. 
The  sheets  unite  when  pressed  together ;  the  remainder  of 
the  process  being  the  same  as  that  employed  for  single 
sheets. 

The  parchment  exhibits  remarkable  differences  to  the 
original  paper,  the  strength  being  increased  three  or  four 
times,  the  density  about  30  per  cent.,  the  latter  being  shown 
by  the  shrinkage,  which  amounts  to  at  least  30  per  cent. 

Vulcanised  Paper. — Zinc  chloride  has  the  property  of 
parchmentising  paper  in  a  manner  similar  to  sulphuric  acid. 
The  product  obtained  when  this  reagent  is  used  is  generally 
termed  vulcanised  fibre.  The  paper  is  passed  as  a  continuous 
sheet  into  a  bath  of  strong  zinc  chloride,  having  a  density 
of  160 — 170  Twaddell,  which  causes  the  cellulose  to  swell 
up  and  partly  gelatinise.  A  very  large  excess  of  strong 
zinc  chloride  is  necessary,  and  the  process  is  only  rendered 
commercially  possible  by  careful  recovery  of  the  zinc  from 
the  washing  waters,  which  are  submitted  to  chemical 
treatment. 

The  vuleajiised  product  is  subsequently  treated  with 
nitric  acid  or  with  a  mixture  of  nitric  and  sulphuric  acids 
to  render  them  waterproof.  Dextrin  is  frequently  employed 
to  retard  the  chemical  action  to  permit  of  the  necessary 
manipulation  of  the  material  before  it  is  finally  washed. 
The  complete  removal  of  the  excess  of  zinc  and  acid  is  a 
necessary  feature  of  the  whole  operation. 

Willesdeii  Paper. — When  paper  is  passed  through  an 
ammoniacal  solution  of  copper  oxide,  a  superficial  gelatinisa- 
tion  of  the  surface  takes  place,  so  that  the  paper  when 
washed  and  dried  is  impregnated  with  copper  oxide,  which 


140 


THE  MANUFACTUEE  OF  PAPEE 


helps  to  preserve  it,  and  it  becomes  waterproof.  Such 
material  is  well  known  as  Willesden  paper. 

Blue  Print  or  Cyanotype  Papers. — This  name  is  usually 
given  to  the  process  by  means  of  which  blue  prints  of 
engineers'  and  architects'  plans  can  be  reproduced.  It  was 
discovered  in  1842  by  Sir  John  Herschel.  It  is  a  useful 
method  of  reproducing  drawings,  and  incidentally  is  of 
great  value  to  the  amateur  photographer  because  of  the 
facility  with  which  it  can  be  applied  for  getting  proofs 
from  negatives  quickly  and  easily  without  special  baths 
and  chemicals.  The  process  is  based  upon  the  reduction 
of  a  ferric  salt  to  the  ferrous  condition  by  light,  and  the 
formation  of  Prussian  blue  by  the  action  of  potassium 
ferricyanide.  The  negative  cyanotype  gives  white  lines 
on  a  blue  ground.    Various  formulae  are  in  common  use. 


Herschel. 

Clark. 

Watt. 

Rock  wood. 

Solution  1. 

Potassium  ferricyanide 

16 

27 

48 

10 

Water  .... 

100 

100 

100 

100 

Ammonia 

2-3 

Saturated     solution  of 

oxalic  acid  . 

20 

Solution  2. 

Ammonia- citrate  of  iron  . 

20 

30 

50 

30 

Water  .... 

100 

100 

100 

100 

Boric  acid 

0-5 

Dextrin  .... 

5 

Equal  parts  of  the  two  prepared  solutions  are  mixed 
when  required  and  spread  evenly  over  well-sized  paper.  The 
paper  is  hung  up,  dried,  and  preserved  in  a  dark  dry  place. 

The  positive  cyanotype  gives  blue  lines  on  a  white  ground, 
being  the  reverse  of  the  ordinary  blue  print.  That  is,  no 
image  is  formed  where  the  light  acts,  and  the  reaction  is 


SPECIAL  KINDS  OF  PAPER 


141 


the  formation  of  blue  due  to  the  union  of  a  ferrous  salt 
with  ferrocyanide  of  potassium. 

PizzighelH  in  1881  gave  the  following  formula : — 


Solution  1. 

Solution  2. 

Solution  3. 

Solution  4. 

Water        .  •  . 

100 

100 

100 

100 

Gum  arabic 

20 

Ammonia- citrate  of  iron  . 

50 

Ferric  chloride  .       .  . 

50 

Potassium  ferrocyanide 

20 

Mix  the  first  three  solutions  in  the  following  order  in  the 
proportions  stated : — 

Solution  1.    20  parts. 
Solution  2.     8  „ 
Solution  3.  5 

As  soon  as  the  solution,  which  at  first  gets  thick  and 
cloudy,  is  clear  and  thin,  it  is  spread  over  the  surface  of 
well-sized  paper,  which  is  then  dried  in  a  warm  room. 

The  print,  which  appears  yellow  on  a  dark  yellow  ground, 
is  treated  with  the  developer  (solution  4)  by  means  of 
a  brush  dipped  in  the  solution.  When  the  image  is  deep 
blue  in  colour,  the  print  is  washed  in  water  and  then  placed 
in  dilute  hydrochloric  acid  (1  part  of  acid  to  10  parts  of 
water)  till  the  ground  is  quite  white.  A  final  washing  with 
water  is  then  necessary. 

Waterhouse  gives  the  following  formula  : — 


Solution  1. 

Solution  2. 

Solution  3. 

Solution  4. 

Water 

650 

150 

100 

Gum  arabic 

170 

Tartaric  acid 

40 

Ferric  chloride  solution  45° 

Beaume  .... 

150 

Ferrocyanide  of  potassium 

20 

142 


THE  MANUFACrUEE  OF  PAPER 


Solutions  1  and  2  are  mixed  and  No.  3  added  gradually 
with  constant  stirring.  The  mixture  is  left  twenty-four 
hours,  and  diluted  with  water  to  a  specific  gravity  of  I'lOO. 

The  paper  is  coated  with  the  solution  and  used  as  already 
directed,  being  developed  in  ferrocyanide  of  potassium 
solution  and  washed  with  water,  treated  with  weak  hydro- 
chloric acid,  and  then  finally  cleaned  from  all  traces  of 
acid. 

Black  Lines  on  a  White  Ground. — This  modification  of 
the  ordinary  blue  print  is  arrived  at  with  the  following 
formula : — 

Water  96*0  parts. 

Gelatine        .       .       .       .       .       .      1*5  ,, 

Perchloride  of  iron  (in  syrupy  condition)      6'0  ,, 
Tartaric  acid         .       .        .       .       .      6*0  ,, 

Sulphate  of  iron    .       .       .       .       .      1*5  „ 

The  pajDer  is  coated  with  the  solution.  After  printing, 
the  image  is  developed  with  a  solution  containing 

Gallic  acid      ...      1  part. 

Alcohol    .       .       .       .10  parts. 

Water     .       .       .       .    50  „ 
A  final  washing  of  the  print  with  water  completes  the 
operation. 

Coated  Papeks. 

This  term  should  properly  include  all  the  varieties  of 
special  papers  which  are  coated  with  extraneous  matter  for 
particular  purposes,  such  as  art,  chromo,  tinfoil,  gilt,  emery, 
carbon,  photographic,  marble,  and  sand  papers.  In  practice 
however,  the  term  is  almost  entirely  limited  to  ''art" 
papers  used  for  illustration  work  and  halt-tone  printing. 

An  "art"  paper,  using  the  definition  given  above,  con- 
sists of  an  ordinary  sheet  of  paper,  one  or  both  sides  of 


SPECIAL  KINDS  OF  PAPER 


143 


which  have  been  coated  by  the  application  of  a  mixture  of 
a  mineral  matter,  such  as  china  clay  or  satin  white,  and 
some  adhesive,  like  casein  or  glue.  The  object  of  the  coat- 
ing is  to  impart  to  the  paper  a  perfectly  smooth  surface, 
rendered  necessary  because  of  the  conditions  under  which 
the  printing  of  the  illustrations  is  carried  out. 


Fig.  44.— General  ariangemeDt  of  Plant  for  making  "Art"  Paper. 

The  machine  used  for  coating  the  i3a2W  consists  of  a 
large  hollow  drum  about  40  inches  diameter  and  48  inches 
wide.  The  paper  is  brought  over  upon  the  drum  in  a  con- 
tinuous sheet,  and  the  coating  mixture  applied  to  the  surface 
by  means  of  a  revolving  brush  or  an  endless  felt  which 
rotates  in  a  copper  trough  containing  a  coating  mixture 
which  is  usually  maintained  at  a  temperature  of  120°  Fahr. 

The  amount  of  material  put  on  to  the  surface  of  the 


144 


THE  MANUFACTUEE  OF  PAPER 


paper  is  varied  by  altering  the  proportion  of  water  in  the 
trough.  As  the  wet  coated  paper  is  drawn  over  the  drum 
it  comes  into  contact  with  a  number  of  flat  brushes  which 
move  from  side  to  side  and  brush  the  coating  well  into  the 
paper. 

The  last  two  or  three  brushes  on  the  drum  are  made  of 
very  fine  bristles,  so  that  when  the  coated  paper  leaves  the 
machine  the  surface  is  perfectly  even  and  free  from  brush 
marks.   The  wet  paper  is  then  drawn  up  an  inclined  ladder 


Fig.  45. — Sectional  Elevation  of  "  Coating"  Plant. 


by  an  ingenious  device,  which  causes  the  paper  to  fall  into 
festoons  or  loops,  and  these  are  carried  bodily  forward  by 
means  of  travelling  chains.  The  process,  somewhat  difficult 
to  describe,  is  more  easily  understood  by  a  study  of  the 
illustrations  given. 

The  paper  is  dried  by  a  current  of  warm  air  which  can 
be  obtained  by  means  of  steam  pipes  placed  below  the 
festoons  or  with  a  special  air  blower.  The  dry  paper  is 
then  led  through  guide  rolls  and  wound  up  in  the  form  of 
a  reel. 

The  paper  at  this  stage  has  a  dull  coated  surface,  which 


SPECIAL  KINDS  OF  PAPEE 


145 


is  somewhat  rough  and  unfinished,  and  a  high  poHsh  is 
imparted  to  it  by  a  machine  known  as  a  supercalender. 

The  supercalender  consists  of  a  number  of  alternate 
steel  and  cotton  or  paper  rolls  placed  vertically  in  a  stack 
one  above  the  other.  When  the  coated  paper  is  led  through 
this  machine  the  friction  of  the  alternate  steel  and  cotton 
rolls  produces  a  high  finish  on  its  surface. 

An  art  paper  coated  on  both  sides  is  manufactured  by 
passing  the  paper  through  the  coating  machine  twice. 
Machines  have  been  devised  for  coating  both  sides  of  the 
paper  at  one  operation,  but  these  are  not  in  very  general 
use. 

Tinted  art  papers  are  prepared  in  the  same  manner,  the 
desired  colour  being  obtained  by  the  addition  of  pigments 
or  aniline  dyes  to  the  mixture  in  the  trough  containing  the 
coating  materials.  When  the  two  sides  of  such  tinted  papers 
are  coloured  differently,  they  are  often  described  as  duplex 
coated  papers. 

Imitation  Art  Papers  are  prepared  by  quite  a  different 
process,  although  they  have  the  appearance,  more  or  less, 
of  the  coated  paper.  They  are  merely  esparto  papers  very 
heavily  loaded,  containing  frequently  as  much  as  25  to  30 
per  cent,  of  mineral  matter  prepared  as  follows : — 

Bleached  esparto  half-stuff  is  beaten  together  with  any 
suitable  proportion  of  chemical  wood  pulp  in  an  ordinary 
beating  engine,  and  a  large  quantity  of  china  clay  is  added 
at  the  same  time.  The  beating  is  carried  out  under  condi- 
tions which  favour  the  retention  of  as  much  china  clay  as 
the  pulp  will  hold  while  being  converted  into  paper  on  the 
Fourdrinier  machine. 

After  the  paper  passes  over  the  drying  cylinders  of  the 
machine  it  is  passed  through  the  calenders  in  the  usual 
way,  but  the  surface  of  the  paper  is  damped  by  means  of  a 
fine  water  spray  just  before  it  enters  the  calender  rolls. 


146 


THE  MANUFACTURE  OE  PAPER 


The  result  is  that  a  "  water-finish,"  so  called,  is  imparted 
to  the  paper,  and  a  close  imitation  of  the  genuine  art  paper 
is  obtained,  the  effect  of  this  peculiar  treatment  being  to 
compress  the  fibres  and  bring  the  clay  up,  as  it  were,  to  the 
surface. 

A  paper  containing  such  a  large  proportion  of  mineral 
matter  intimately  mixed  with  the  fibre  is  naturally  very 
weak.  It  easily  tears,  and  if  moistened  with  water  goes  all 
to  pieces.  At  the  same  time  it  is  a  cheap  substitute  for 
high-class  art  paper,  being  suitable  for  circulars,  temporary 
catalogues,  and  similar  printed  matter. 

In  an  "  art "  paper  the  nature  of  the  fibrous  constituents 
is  too  often  regarded  as  a  matter  of  secondary  importance, 
because  in  the  process  of  printing  the  ink  does  not  come 
into  contact  at  all  with  the  paper,  and  an  impression  is 
produced  merely  on  a  layer  of  clay  which  is  bound  together 
by  the  glue. 

The  illustrations  are  not  absolutely  permanent,  and  it  is 
perfectly  easy  to  remove  the  whole  of  the  impression  and 
the  coating  itself  by  immersing  a  sheet  of  the  paper  in 
warm  water  and  rubbing  the  surface  gently  with  the  fingers, 
or  with  a  camel-hair  brush. 

In  fact  the  amount  of  coating  matter  which  has  been 
brushed  on  to  a  paper  can  be  determined  apjoroximately  by 
weighing  a  piece  of  the  coated  paper,  removing  the  mineral 
matter  and  glue  from  both  sides  as  indicated,  allowing  the 
paper  to  dry  again,  and  then  re-weighing,  the  loss  in  weight 
representing  the  amount  of  coating. 

It  is  not  surprising  to  find  that  the  true  paper  is  merely 
regarded  as  a  convenient  means  of  producing,  so  to  speak, 
a  smooth  surface  of  clay,  and  an  examination  of  the 
material  between  the  two  clay  surfaces  often  reveals  a 
paper  of  very  low  quality. 

There  are  one  or  two  empirical  methods  for  testing  the 


SPECIAL  KINDS  OF  PAPER 


147 


condition  of  coating  on  an  art  paper.  If  the  coating  is  firm 
and  adherent,  then  on  pressing  the  moistened  thumb  on  to 
the  surface  none  of  the  coating  matter  is  removed,  bat  in 
a  badly-made  art  paper  some  of  the  coating  adheres  to  the 
thumb. 

Another  method  is  to  crumple  a  sheet  of  paper  between 
the  fingers,  and  if  any  of  the  coating  comes  away  easily  the 
paper  is  considered  of  -poor  quality. 

The  complete  examination  of  an  art  paper,  apart  from 
the  practical  test  of  printing,  involves  the  determination  of 
the  amount  of  coating  matter  added  to  the  paper,  the  pro- 
portion of  glue  in  the  coating,  and  the  usual  analysis  of  the 
paper  itself. 

Packing  Papers. 

This  term  may  be  applied  to  wrappings  specially  treated 
with  substances  which  render  the  paper  air  and  water  proof. 
They  are  principally  used  for  preserving  food,  or  such 
articles  as  tobacco,  which  require  to  be  kept  slightly 
moist. 

Waxed  Paper.—  The  paper  in  the  form  of  a  continuous 
sheet  is  passed  through  a  bath  of  melted  wax  at  a  high 
temj^erature,  any  excess  being  removed  by  squeezing  rolls 
through  which  the  hot  waxed  paper  is  passed.  The  paper 
is  led  over  skeleton  drums  and  thoroughly  cooled  before 
being  cut  into  sheets. 

Butter  Paper. — Ordinary  parchment  paper  is  generally 
used,  but  for  special  purposes  a  solution  containing  albumen 
and  saltpetre  is  utilised  for  impregnating  paper. 

Hardware  Paper. — Needles  and  silver  goods  are  fre- 
quently wrapped  in  paper  impregnated  or  mixed  with 
substances  which  are  supposed  to  prevent  deleterious  fumes 
from  coming  into  contact  with  them.  The  use  of  black  papers 

L  2 


148 


THE  MANUFACTURE  OF  PAPEE 


heavily  loaded  with  pigment,  sized  with  glue  and  an  excess 
of  alum,  is  commonly  resorted  to.  For  silver  ware,  paper 
dipped  in  a  solution  of  caustic  soda  containing  zinc  oxide 
is  used.  A  recent  patent  suggests  the  impregnation  of 
paper  with  heavy  hydrocarbon  oils,  which  being  slightly 
volatile  cover  the  goods,  such  as  needles,  with  a  thin 
film. 

Paraffin  Paper. — Large  quantities  of  this  paper  are  con- 
sumed for  packing  food  and  other  articles  which  need 
protection  from  air  and  moisture. 

The  paper  is  either  passed  through  a  bath  of  paraffin 
or  passed  over  a  roller  which  rotates  in  a  trough  of 
paraffin. 

If  the  paper  is  to  be  coated  on  both  sides  it  is  passed 
through  the  bath  containing  the  paraffin  in  a  melted  con- 
dition, the  excess  of  which  is  scraped  from  the  paper  as  it 
leaves  the  bath.  The  paper  is  cooled  by  exposure  to  air, 
and  when  the  paraffin  has  solidified  upon  the  sheet 
the  paper  is  wound  up  on  a  roller  at  the  end  of  the 
machine. 

If  the  paper  is  to  be  coated  on  one  side  only  it  is  passed 
over  a  heated  roller  which  revolves  in  a  bath  of  melted 
paraffin,  the  other  operations  of  drying  and  finishing 
being  the  same  as  in  the  case  of  a  paper  coated  on  both 
sides. 

Tinfoil  Papers,  required  for  packing  tea,  coffee,  and 
similar  foodstuffs,  are  prepared  by  coating  cheap  paper 
with  a  solution  of  gum  and  finely  powdered  tin.  The 
manufacture  of  the  fine  powder  is  accomplished  by  melting 
tin  at  a  low  temperature  and  shaking  it  continually  as  it 
cools  down,  whereby  a  mixture  of  fine  powder  and  large 
particles  is  produced,  the  latter  being  separated  out  by 
agitation  of  water. 

Tin  in  a  fine  state  of  division  can  also  be  obtained  by  a 


SPECIAL  KINDS  OF  PAPER 


149 


chemical  process.  Granulated  tin  is  dissolved  in  strong 
hydrochloric  acid,  the  solution  diluted  with  water,  and  a 
stick  of  zinc  introduced  into  the  solution.  The  tin  is 
gradually  precipitated. 

The  dried  powder  is  coated  on  to  the  paper  with  gum, 
and  when  the  paper  is  dry  the  necessary  degree  of  brilliancy 
produced  by  suitable  calendering. 

Transfer  Papers. — A  number  of  important  operations 
require  the  use  of  what  are  known  as  transfer  papers,  so 
that  a  design  written  or  printed  upon  a  specially  prepared 
surface  can  be  transferred  to  another  surface  from  which 
duplicate  copies  may  be  obtained.  The  principle  upon 
which  all  such  operations  are  based  is  the  coating  of  suit- 
able paper  with  starch,  flour,  and  gum,  singly  or  mixed, 
so  as  to  give  a  surface  firm  enough  to  take  the  design, 
but  which  readily  breaks  up  when  the  printed  side  is 
pressed  against  the  wood,  stone,  or  metal  object  intended 
to  receive  the  design. 

Thus  a  paper  may  first  be  dusted  over  with  dry  starch,  or 
coated  with  starch  paste  and  then  dried.  A  layer  of  dextrine 
may  then  be  put  over  the  starch  coating,  and  the  design 
printed  upon  the  dextrine  surface.  When  the  paper  is  turned 
face  downward  on  a  sticky  metal  plate  the  design  adheres 
to  the  metal,  and  the  paper  is  easily  pulled  off,  owing  to 
the  dry  starch  layer  between  it  and  the  dextrine  being  non- 
adhesive. 

This  principle  is  utilised  in  producing  designs  upon  tins 
used  for  packing,  metal  advertisement  plates,  domestic 
articles  of  every  kind,  stoneware  and  earthenware 
goods. 

It  is  further  applied  in  the  preparation  of  lithographic 
stones  required  for  printing. 

Each  class  of  work  demands  paper  of  a  suitable  character, 
but  the  principle  of  an  easily  detached  surface-coating  is  the 


150 


THE  MANUFACTUEE  OF  PAPER 


same  for  all.  The  main  difficulty  experienced  is  the  liability 
of  paper  to  stretch  when  damped,  and  various  methods  are 
devised  to  obviate  this,  either  by  employing  paper  which 
stretches  very  little  when  damp,  or  by  making  the  paper 
partially  waterproof  before  use. 

Papier-mdcM. — This  name  indicates  a  preparation  of 
paper  or  paper  pulp  mixed  with  various  mineral  sub- 
stances firmly  cemented  together  by  animal  or  vegetable 
adhesives. 

The  jmper  jyiilp  used  for  high-class  goods  consists  of  pure 
wood  cellulose,  while  for  the  commoner  qualities  mechanical 
wood  pulp,  waste  papers,  and  any  similar  fibrous  material 
are  employed. 

The  mineral  substances  used  are  china  clay,  chalk, 
gypsum,  barytes,  ochre,  sienna,  and  other  mineral  pig- 
ments. 

The  adhesive  materials  are  glue,  casein,  gum,  starch, 
paste,  dextrine,  Iceland  moss,  or  wax. 

For  experimental  purposes,  small  quantities  of  papier- 
mache  may  be  prepared  in  the  following  manner  : — 

When  old  newspapers  or  brown  papers  are  used  as  the 
fibrous  basis  of  the  papier-mache,  they  are  first  torn  up 
into  small  pieces,  moistened  with  hot  water,  tied  up  in  a 
small  cloth  bag  or  sack,  which  must  only  be  half  filled, 
and  then  immersed  in  a  basin  of  warm  water  and  thoroughly 
kneaded  by  hand,  so  that  the  paper  is  gradually  reduced  to 
the  condition  of  pulp.  If  the  kneading  process  is  carried 
out  thoroughly  the  paper  is  entirely  reduced  to  pulp. 
The  excess  of  w^ater  can  be  removed  by  pressure  and 
the  preparation  of  the  final  mixture  completed  by  the 
incorporation  of  clay,  pigment,  and  adhesive. 

In  the  preparation  of  papier-mache  for  goods  on  a  large 
scale  a  beating  engine  is  used  in  order  to  break  up  the  old 
paper  or  wood  pulp  into  a  fibrous  condition. 


SPECIAL  KINDS  OF  PAPER  151 

The  following  formulfp.  can  be  used  for  making  papier- 
mache  : — 


(1) 

(2) 

(3) 

(4) 

Pulp  . 

.  22 

Pulp 

22 

Pulp 

12 

Pulp  . 

.  33 

Clay_  . 

.  37 

Chalk 

30 

Eosin  size 

22 

starch 

9 

Casein 

.  37 

aiue 

4 

Flour 

11 

Clay  . 

.  9 

Water 

4 

Water 

44 

China  clay 

11 

Water 

.  49 

Water  . 

44 

100 

100 

100 

100 

Plaster  Moulds. — Plaster  of  Paris  or  gypsum  is  the  main 
article  used  for  moulds  and  pattern.  The  preparation  of 
gypsum  for  casting  is  made  as  follows  : — The  gypsum  is 
gradually  worked  up  into  a  creamy  paste  with  water,  the 
mixing  being  done  quickly  yet  thoroughly. 

The  pattern  of  which  it  is  desired  to  form  a  mould  must 
be  coated  with  oil.  Around  the  pattern  placed  on  a  table  a 
wall  of  wood  or  pasteboard  is  fixed,  so  that  a  basin  will  be 
formed  of  suitable  depth,  preventing  the  gypsum  from 
flowing  away.  Patterns  of  figures  or  of  curved  articles 
have  to  be  made  in  two  or  more  parts.  For  that  purjDOse 
the  pattern  is  usually  cut  into  two  pieces.  Two  moulds  are 
now  readily  obtainable  by  first  oiling  the  pattern  and  by 
pouring  the  gypsum  in  a  thin  state  gradually  over  the 
surface,  to  avoid  the  forming  of  air  bubbles. 

The  rapid  drying  of  the  soaked  gypsum  is  sometimes 
inconvenient,  but  the  addition  of  a  saturated  solution  of 
borax  in  water  to  the  gypsum  mixture  can  be  resorted  to  as 
a  check. 

Various  means  are  employed  for  hardening  and  strength- 
ening the  plaster  cast,  such  as  the  addition  of  coarse  paper 
fibres,  shreds  of  canvas,  iron  filings,  or  wire, 


152 


THE  MANUFACTUEE  OF  PAPER 


Colouring. — Usually  a  cheap  water  colour  only  is  required  ; 
a  light  coating  of  a  cheap  varnish  may  be  sufficient. 
In  other  cases  a  water  colour  serving  as  a  filler  for 
smoothing  the  surface  may  receive  a  finish  of  one  or  more 
coats  of  resinous  solutions  in  alcohol  or  of  copal  varnish. 
Many  goods  are  coated  with  asphaltum  or  Japan  varnish 
and  dried  in  cold  or  hot  air. 

Some  of  the  articles  may  be  decorated  with  scrolls  or 
arabesques  in  oil  colours  or  enamels,  or  the  lines  may 
be  covered  with  bronze  powder,  or  with  metal,  gold,  or 
aluminium  leaf. 

Varnishing. — The  following  varnish  recipes  are  suit- 
able : — 


(1) 

(2) 

(3) 

(4) 

Shellac 

20 

Shellac 

.  10 

Shellac 

.  6 

Sandarac  . 

15 

Alcohol 

70 

Rosin 

.  10 

Sandarac 

.  3 

Mastic 

5 

Lamp  black 

10 

Alcohol 

.  60 

Mastic 

.  18 

Turpentine . 

5 

Lampblack  20 

Alcohol 

73 

Alcohol 

75 

100 

100 

100 

100 

CHAPTER  VIII 


CHEMICALS    USED    IN  PAPER-MAKING 

The  manufacture  of  paper  is  a  highly  technical  industry, 
which  requires  a  practical  knowledge  of  mechanical  engineer- 
ing, as  well  as  an  intimate  acquaintance  with  the  many 
important  chemical  problems  connected  with  the  art. 

The  following  brief  description  of  the  various  chemicals 
used  in  the  manufacture  of  paper  is  divided  into  certain 
classes,  based  upon  the  order  of  the  operations  through 
which  the  raw  material  passes  before  its  final  conversion 
into  paper : — 

(1)  The  alkaline  processes  used  for  treating  raw  fibre  : 
soda  ash  ;  caustic  soda  ;  lime;  recovered  ash. 

(2)  The  conversion  of  wood  into  sulphite  pulp  :  sulphur  ; 
limestone. 

(3)  The  operation  of  bleaching :  bleaching  powder ; 
antichlors  ;  acids. 

(4)  The  sizing  and  loading  of  paper :  casein ;  gelatine ; 
rosin  size ;  alum  ;  starch  ;  silicate  of  soda  ;  pigments 
and  soluble  dyes  ;  mordants. 

Mineral  substances  for  loading:  clay,  blanc  fixe,  etc. 

Carbonate  of  Soda. — This  substance,  also  known  under 
the  trade  names  of  alkali  and  soda  ash,  is  used  in  the 
paper  mill  for  the  manufacture  of  caustic  soda.  It  is 
purchased  by  the  paper-maker  from  the  chemical  works, 
and  used  together  with  the  recovered  ash  (see  page  78)  for 
the  production  of  caustic  soda  solution,  which  is  required 
in  the  treatment  of  raw  fibres. 


154 


THE  MANUFACTURE  OF  PAPER 


It  is  also  used  for  the  preparation  of  rosin  size  (see 
"  Eosin  Size  ")  and  in  softening  hard  waters  for  steam -raising 
purposes. 

Sodium  Carbonate  Table. 


Showing  percentage  by  weight  and  pounds  per  100  gallons  in 
solutions  of  various  densities. 


Percentage  by  Weight. 

100  gallons  contain  pounds  of 

1  waadell. 

"Mo,  r» 
JNa2  U. 

Na2  O. 

Nan  POo 

1 
1 

0-28 

0-47 

2-76 

4-72 

5-74 

9 

0-56 

0-95 

5-61 

9-60 

11-68 

') 
o 

0-84 

1-42 

8-42 

14-41 

17-56 

A 

t: 

1-11 

1-90 

11-34 

19-38 

23-64 

0 

1-39 

2-38 

14-26 

24-40 

29-73 

O 

1-67 

2-85 

17-10 

29-36 

35-77 

/ 

1-95 

3-33 

20-16 

34-46 

42-00 

o 

o 

2-22 

3-80 

23-12 

39-52 

48-15 

Q 

2-50 

4-28 

26-17 

44-72 

54-50 

2-78 

4-76 

29-71 

50-00 

60-90 

1  1 
i  1 

3-06 

5-23 

32-27 

55-18 

67-22 

1  9 

3-34 

5-71 

35-36 

60-50 

73-72 

13 

3-61 

6-17 

38-43 

65-72 

80-07 

14 

3-88 

6-64 

41-57 

71-06 

86-58 

15 

4-16 

7-10 

44-65 

76-33 

93-03 

16 

4-42 

7*57 

47-80 

81-77 

99-61 

17 

4-70 

8-04 

51-02 

87-24 

106-31 

18 

4-97 

8-51 

54-25 

92-74 

113-10 

19 

5-24 

8-97 

57-45 

98-26 

119-70 

20 

5*52^ 

9-43 

60-67 

103-70 

126-42 

21 

5-79 

9-90 

63-98 

109-40 

133-45 

22 

6-06 

10-37 

67-32 

115-10 

140-12 

23 

6-33 

10-83 

70-63 

120-81 

14710 

24 

661 

11-30 

74-00 

126-62 

154-20 

25 

6-88 

11-76 

77-38 

132-30 

161-12 

26 

7-15 

12-23 

80-83 

13N-20 

168-51 

27 

7-42 

12-70 

84-31 

144-12 

175-70 

28 

7-70 

13-16 

87-67 

150-20 

182-70 

29 

7-97 

13-63 

91-28 

156-15 

190  14 

30 

8-24 

14-09 

94-77 

162-00 

197-40 

Analysis. — The  value  of  soda  ash,  carbonate  of  soda,  and 
recovered  ash  depends  on  the  amount  of  available  alkali 
(Na2  0)  present. 


CHEMICALS  USED  IN  PAPEE-MAKINa 


155 


A  weighed  quantity  (15*5  grammes  conveniently)  is 
dissolved  in  a  measured  volume  of  distilled  water  (500  c.c), 
and  titrated  with  standard  normal  hydrochloric  acid,  methyl 
orange  indicator  being  used. 

Caustic  Soda. — Raw  vegetable  fibres  may  be  reduced  to 
the  condition  of  paper  pulp  by  treatment  with  caustic  soda. 
In  practice  this  process  is  largely  resorted  to  for  the 
manufacture  of  pulp  from  esparto,  straw,  and  wood,  the 
spent  caustic  soda  being  recovered  and  used  again. 

The  paper-maker  prepares  the  caustic  required  for  digest- 
ing the  raw  material  from  recovered  ash  and  carbonate 
of  soda. 

A  convenient  volume  of  clear  liquor  obtained  by  lixiviating 
the  recovered  ash  is  boiled  with  lime  in  suitable  causticising 
pans,  the  reaction  being  represented  as  follows  : — 

Na2  CO3   +  Ca  0  +  H2  0    =  2  Na  OH      +  Ca  CO3. 
Soda  ash  +  Lime  +  Water  =  Caustic  soda  +  Chalk. 

According  to  this  equation,  100  lbs.  of  soda  ash  require 
53  lbs.  of  quicklime,  but  a  slight  excess  is  generally  added, 
58  or  60  lbs.  being  the  usual  amount  actually  employed. 
Several  precautions  should  be  observed  in  the  process  of 
causticising. 

(1)  The  liquor  from  the  recovered  soda  should  be  bright 
and  clear,  indicating  complete  incineration  of  the  ash. 

(2)  The  liquor  is  best  causticised  at  a  density  between 
1;050  and  1-100  (10— 20,Twaddell).  With  stronger  solutions 
the  reaction  is  complicated  and  the  yield  of  caustic  soda 
reduced.  Lunge  has  shown  that  if  the  density  of  the 
solution  is  1*025  the  proportion  of  soda  causticised  is 
99*5  per  cent.,  whereas  at  a  density  of  1*150  it  is  only 
94'5  per  cent.  In  the  latter  case  the  caustic  soda  formed 
acts  upon  the  chalk  j^t'oduced  and  is  reconverted  into 
carbonate. 


156 


THE  MANUFACTURE  OF  PAPER 


(3)  The  large  quantities  of  chalk  residue  resulting  from 
the  reaction  must  be  thoroughly  and  carefully  washed. 
The  economy  of  the  whole  process  depends  in  no  small 
measure  upon  this  seemingly  small  detail. 

Caitstic  Soda  Tables. 


Showing  quantity  of  liquor  obtained  from.  1  cwt.  of  caustic  soda  and 
the  amount  of  caustic  soda  in  100  gallons  of  liquor  (adapted  from 
Lunge  and  others) . 


Twaddell. 

Gallons  obtained  per  hundred- 
weight of  Caustic. 

Twaddell. 

Pounds  of  Caustic  Soda  per 
100  gallons  Liquor. 

GO  per  cent. 
Caustic, 

VT  per  cent. 
Caustic  Pure. 

60  per  cent. 
Caustic. 

77  per  cent. 
Caustic  Pure. 

1 

i 

1,777 

2,358 

1 
i 

6-3 

4-75 

2 

896 

1,179 

2 

12-5 

9-5 

3 

596 

767 

3 

18-8 

14-6 

4 

448 

574 

4 

25-0 

19-5 

5 

359 

457 

5 

31-2 

24-5 

6 

298 

384 

6 

37-6 

29-2 

7 

256 

330 

7 

43-8 

34-0 

8 

223 

287 

8 

501 

39-0 

9 

199 

256 

9 

56-2 

43-7 

10 

178 

229 

10 

62-9 

48-9 

11 

162. 

208 

11 

69-1 

53-7 

12 

148 

190 

12 

75-7 

58-7 

13 

136 

176 

13 

82-1 

63-7 

14 

126 

166 

14 

88-5 

67-5 

15 

117-5 

152 

15 

95  0 

73-5 

16 

110 

141-5 

16 

101-5 

79-0 

17 

103-5 

135 

17 

107-8 

83-0 

18 

98 

125-5 

18 

114-4 

89-0 

19 

92-8 

119-5 

19 

120-8 

93-8 

20 

88 

114 

20 

127-2 

98-0 

25 

70 

90-3 

25 

159-5 

124-0 

30 

56-5 

73 

30 

197-3 

1530 

35 

48 

61-5 

35 

234-9 

182-2 

40 

41 

53 

40 

272-6 

211-6 

45 

35-3 

45-5 

45 

317-4 

246-3 

50 

31 

40 

50 

362-1 

2^1-0 

CHEMICALS  USED  IN  PAPER-MAKING  157 


Dilution  Table  for  Strong  Liquors. 


Showing  number  of  gallons  of  water  required  to  reduce  the  density 
of  100  gallons  of  liquor  from  a  higher  density,  D,  to  a  lower 
density,  d.    (See  page  163). 


Lower  Density,  d. 

Ob 

14. 

13. 

12. 

11. 

10. 

9. 

8. 

7. 

6. 

5. 

4. 

42 

200 

223 

250 

281-8 

320 

367 

425 

500 

600 

740 

950 

40 

185 

207 

233-3 

263-6 

300 

344-4 

400 

471-4 

566-6 

700 

900 

38 

171 

192 

216-6 

245-5 

280 

322-2 

375 

442-8 

533-3 

(;60 

850 

36 

157 

177 

200 

227-3 

260 

300 

350 

414-3 

500 

620 

800 

34 

143 

161-5 

183-3 

209-1 

240 

277-7 

325 

385-7 

466-6 

580 

750 

32 

128-6 

146 

166-6 

191 

220 

255-5 

300 

357-1 

433-3 

540 

700 

30 

114-3 

130-6 

150 

172-8 

200 

233-3 

275 

328-5 

400 

500 

650 

28 

100 

115-3 

133-3 

154-6 

180 

211-1 

250 

300 

366-6 

460 

600 

26 

85-7 

100 

116-6 

136-4 

i(;o 

188-S 

225 

271-4 

333-3 

420 

550 

24 

71-4 

84-6 

100 

118-2 

140 

1  (;(;-(; 

200 

243 

300 

380 

500 

22 

57-1 

69-2 

83-3 

100 

120 

144-4 

175 

214-4 

2(')6-() 

340 

450 

20 

43 

53-6 

(56-6 

81-8 

100 

122-2 

150 

185-7 

233-3 

300 

400 

18 

28-6 

38-4 

50 

63-7 

80 

100 

125 

157 

200 

260 

350 

16 

14-3 

23 

33-3 

45-5 

60 

77-7 

100 

128-5 

166-6 

220 

300 

Lime  and  Limestone. — Carbonate  of  soda  and  recovered 
ash  are  converted  into  caustic  soda  by  means  of  lime. 
About  sixty  parts  of  lime  are  necessary  for  the  conversion 
of  100  parts  of  carbonate  of  soda.  Large  quantities  of 
insoluble  carbonate  of  lime  are  produced  in  this  opera- 
tion, and  great  care  is  necessary  to  prevent  a  loss  of 
caustic  soda  which  occurs  if  the  residue  is  not  thoroughly 
washed.  In  some  cases  the  residual  chalk  is  drained  by 
vacuum  filters  in  order  to  remove  all  traces  of  soluble 
alkali.  Processes  have  been  devised  for  calcining  the 
residue  so  as  to  convert  the  carbonate  into  caustic  lime 
to  be  used  over  again,  but  no  economical  and  practical 
method  has  yet  been  found.  The  treatment  of  the  residual 
chalk  with  sulphuric  acid  for  the  production  of  calcium 
sulphate  appears  feasible,  but  the  substance  obtained  is 
very  impure,  and  therefore  has  little  commercial  value. 


158 


THE  MANUFACTUEE  OF  PAPEE 


Limestone  is  required  in  considerable  quantity  for  the 
preparation  of  sulphite  of  lime  for  the  manufacture  of 
wood  pulp. 

Recovered  Ash. — The  black  liquor  obtained  during  the 
process  of  the  boiling  of  straw,  esparto,  and  other  paper- 
making  fibres  contains  a  large  proportion  of  non-fibrous 
organic  constituents  derived  from  the  fibres,  the  quantity 
of  which  may  be  gauged  from  the  fact  that  these  fibres 
generally  lose  50  per  cent,  of  their  weight  when  being 
boiled.  The  black  liquor  on  evaporation  yields  a  thick 
resinous  mass,  which  is  converted  into  carbonate  of  soda 
when  burnt. 

Advantage  is  taken  of  this  fact  to  carry  out  a  process  of 
incineration  on  a  large  scale,  so  that  heat  derived  from  the 
burning  off  of  the  resinous  mass  is  utilised  for  evaporation 
of  weaker  liquors.  The  ash  is  drawn  from  special  furnaces, 
put  aside,  and  allowed  to  char  quietly,  so  that  the  car- 
bonaceous matter  is  more  or  less  completely  burnt  away. 
The  ash  in  this  form  contains  about  40  per  cent,  of  soda, 
its  composition  being  determined  by  the  nature  of  the  fibre 
which  has  been  treated.  In  the  case  of  straw,  the  amount 
of  silicate  is  considerable,  as  shown  by  the  following  typical 


analysis : — 

Sodium  carbonate      .       .       .       .       .  70*2 

Sodium  hydrate   2*3 

Sodium  sulphate  .....  4*1 
Sodium  chloride        .       .       .       .  .7*5 

Silica         .   7-5 

Oxides  of  iron  and  alumina       .       .       .  0*75 

Unburnt  carbon,  etc   7*65 


lOO'OO 

At  the  present  time  there  is  no  process  in  general  use  for 
the  recovery  of  the  liquors  used  in  the  treatment  of  wood 


CHEMICALS  USED  IN  PAPER-MAKING 


159 


by  the  sulphite  process.  Many  schemes  have  been  proposed, 
the  most  promising  of  which  is  that  of  Drewsen. 

Sulphur  and  Sulpliites. — The  pale  yellow  brittle  substance 
known  as  sulphur  is  too  familiar  to  require  any  detailed 
description.  It  unites  with  oxygen  in  various  proportions, 
and  these  in  contact  with  water  form  the  various  sulphur 
acids  known  to  commerce.  Sulphur  burned  with  a  limited 
quantity  of  air  forms  sulphurous  acid  gas,  and  this  substance 
is  the  chief  product  of  oxidation,  which  by  further  treatment 
can  be  converted  into  sulphites. 

In  the  manufacture  of  the  sulphur  compounds  required 
in  the  preparation  of  wood  pulp,  the  furnace  for  burning 
the  sulphur  consists  of  a  flat-bottomed  cast  iron  retort 
which  is  very  shallow,  and  provided  with  a  curved  top,  to 
which  a  pipe  is  fixed,  so  that  the  sulphurous  acid  may  be 
conveyed  away  from  the  furnace.  In  the  most  recent  form 
of  sulphur  oven  a  small  conical-shaped  revolving  furnace 
is  employed,  which  produces  a  satisfactory  gas  of  constant 
composition  very  economically. 

Bisulphite  of  Lime. — This  compound  is  obtained  when 
the  sulphurous  acid  gas  is  brought  into  contact  with 
moistened  limestone.  In  the  manufacture  of  bisulphite  of 
lime  on  a  large  scale  the  sulphurous  acid  gas  is  drawn  or 
pumped  up  tall  circular  towers  filled  with  blocks  of  lime- 
stone, kept  moistened  by  a  carefully  regulated  stream  of 
water  flowing  from  the  top  of  the  tower. 

In  another  system  known  as  the  acid  tank  process,  the 
gas  is  forced  into  large  circular  vats  containing  milk  of 
lime. 

In  either  case  a  solution  is  prepared  containing  bisulphite 
of  lime,  together  with  a  certain  proportion  of  free  sulphurous 
acid,  the  object  of  the  pulp  manufacturer  being  to  obtain  a 
solution  containing  as  large  a  proportion  of  free  sulphurous 
acid  as  possible.    The  composition  of  a  solution  will  vary 


160 


THE  MANUFACTUEE  OF  PAPEE 


on  this  account,  and  the  following  may  be  quoted  as  being 
an  examjDle  of  such  a  liquor  : — 

Free  sulphurous  acid       .       .       3*23  per  cent. 
Combined  sulphurous  acid       .  0*77 

4-00  „  „ 

For  experimental  purposes  the  bisulphite  of  lime  solution 
may  be  prepared  by  passing  sulphurous  acid  gas  into  a 
mixture  of  water  and  sulphite  of  lime.  The  latter  compound 
is  insoluble  in  water,  but  gradually  dissolves  when  the  gas 
is  absorbed.  A  known  weight  of  sulphite  of  lime  is  added 
to  a  measured  volume  of  water,  and  the  sulphurous  acid 
gas  discharged  into  the  mixture  from  a  siphon  of  com- 
pressed sulphurous  acid.  The  amount  of  gas  absorbed  is 
determined  by  weighing  the  siphon  before  and  after  use, 
the  loss  of  weight  representing  the  gas  discharged. 
The  following  figures  may  be  quoted  as  an  example  : — 

Quantities  used. 

Calcium  sulphite         .       .       .    536  grammes. 

Water  7100  c.c. 

Gas  absorbed      ....    534  grammes. 

Density  of  solution      .       .       .    18°  Twaddell. 

The  composition  of  the  solution  prepared  is — 

Combined  sulphurous  acid  .  .  .  3*50 
Free  sulphurous  acid       .       .       .  .6*54 

Lime  3*06 

Water  86*90 

10000 

Analysis. — The  examination  of  sulphite  liquors  for  free 
and  combined  sulphurous  acid  is  made  by  means  of  stan- 
dard iodine  solution  and  normal  caustic  soda  solution. 


CHEMICALS  USED  IN  PAPEE-MAKINa 


161 


A  known  volume  of  the  sulphite  liquor  is  first  titrated 
with  standard  iodine  solution,  the  number  of  cubic  centi- 
metres required  being  a  measure  of  the  total  sulphurous  acid. 

Each  cubic  centimetre  standard  iodine  solution  =  '0032 
grammes  SO2.  The  titrated  liquor  is  then  treated  with 
standard  caustic  soda  in  quantity  sufficient  to  exactly 
neutralise  the  acid.  The  volume  of  caustic  soda  solu- 
tion used  minus  the  number  of  cubic  centimetres  of  iodine 
first  added  is  a  measure  of  the  free  sulphurous  acid. 

BleachiiKj  Powder. — This  substance  is  prepared  on  a 
large  scale  by  allowing  chlorine  gas  to  act  upon  dry 
slaked  lime.  The  lime  absorbs  nearly  one-half  its  weight 
of  chlorine  and  forms  a  dry  white  powder,  having  a  very 
})ungent  odour.  The  best  bleaching  powder  contains  about 
87  per  cent,  of  what  is  termed  "  available  chlorine."  The 
substance,  on  being  treated  with  w^ater,  gives  a  greenish- 
coloured  solution  known  as  bleach  liquor,  and  when  raw 
paper-ujaking  material,  after  having  been  digested  with 
caustic  soda,  is  treated  with  this  solution,  it  is  gradually 
bleached  to  a  white  colour.  The  composition  of  the  powder 
may  be  represented  approximately  as  follows : — 

Available  chlorine  (combined  with  lime)  .  36*00 
Chlorine  in  the  form  of  chloride  .  .  0'32 
Chlorine  in  the  form  of  chlorate  .  .  0'2G 
Lime       .......  44*66 

Magnesia  0*43 

Silica,  iron  oxides,  etc.  ....  1*33 
Insoluble  matter  17*00 

100*00 

Since  the  amount  of  bleach  used  for  wood  pulps  varies 
from  8  per  cent,  to  25  per  cent,  of  powder  on  the  dry  w^ood 
pulp,  the  cost  of  bleaching  in  some  cases  is  considerable. 
The  economy  of  the  process  depends  in  some  measure 

p.  M 


162 


THE  MANUFACTURE  OF  PAPER 


upon  the  care  exercised  in  the  purchase  of  bleaching  powder 

of  standard  quaUty,  the  storage  of  same  in  a  dark,  cool 

place,  and  the  efficient  treatment  or  exhaustion  of  the 

powder  when  the  bleach  liquor  is  prepared. 

The  powder  is  usually  agitated  for  about  an  hour  with 

water  sufficient  to  produce  a  liquor  of  13° — 15°  Twaddell. 

The  undissolved  powder  is  allowed  to  settle  and  the  clear 

solution  siphoned  off,  after  which  the  sediment  is  washed 

once  or  twice  to  remove  all  the  soluble  matter  completely. 

Bleach  Liquor  Table. 

Showing  for  bleaching  powder  solutions  of  known  density  the  quantity 
of  powder  necessary  to  produce  100  gallons  of  liquor  and  the 
number  of  gallons  obtained  from  1  cwt.  of  powder  (adapted  from 
Lunge  and  Beichofen). 


T*v?i(l(l('ll. 

Available 
Chlorine. 
]'i)unds  per 
100  galloiiss. 

Number  of  Gallons  obtained 
from  112  lbs.  of  Powder. 

Pounds  of  Powder  jier  100 
gallons  of  Liquor. 

.'54  per  cent. 
Powder. 

35  per  cent. 
Powder. 

34  per  cent. 
Powder. 

35  per  cent. 
Powder. 

0-25 

0-70 

5,464 

5,600 

2-05 

2-00 

O-oO 

1-40 

2,725 

2,800 

4-11 

4-00 

1 

2-71 

1,405 

1,445 

7-97 

7-74 

2 

5-58 

681 

702 

16-41 

15-94 

3 

8--J8 

4-18 

462 

24-95 

24-23 

4 

11-41 

334 

340 

33-55 

32-60 

o 

14-47' 

264 

270 

42-58 

41-34 

6 

17-36 

219-5 

225 

51-06 

49-60 

7 

20--J4 

186 

191 

60-11 

58-40 

8 

23*75 

160 

165 

69-85 

67-85 

9 

26-62 

141 

147 

78-30 

76-57 

10 

29-60 

129 

132-5 

87-06 

84-54 

11 

32-68 

116*5 

120 

96-11 

93-37 

12 

35-81 

106-5 

109-5 

105-32 

102-31 

i;3 

39-10 

98 

100 

115-00 

111-70 

14 

42-31 

90 

92-5 

124-45 

120  90 

15 

45'70 

84 

86 

134-41 

130-56 

1(3 

48-96 

78 

80 

143-80 

139-71 

17 

52-27 

73*5 

75 

153-53 

149-34 

18 

55-18 

69 

71 

162-30 

157-65 

19 

58-40 

65  5 

67 

171-00 

166-86 

20 

61-50 

61-5 

64 

180-88 

175-71 

CHEMICALS  USED  IN  PAPER-MAKING 


163 


The  best  method  for  extracting  powder  is  to  agitate  the 
material  with  water  for  a  short  period,  and  to  stop  the 
mixing  process  directly  the  maximum  density  has  been 
obtained,  which  usually  takes  place  in  15  minutes.  Pro- 
longed agitating  prevents  the  powder  from  settling  readily. 

The  maximum  quantities  of  liquor  which  can  be  obtained 
from  bleaching  powder  are  shown  on  page  162.  The 
following  table  is  useful  as  showing  the  amount  of  water 
required  for  diluting  strong  liquors,  the  figures  being 
applicable  to  any  solution  independent  of  the  nature  of 
the  dissolved  substance. 

Dilution  Table  fok  Weak  Liquors. 


Showing  number  of  gallons  of  water  required  to  reduce  the  density 
of  100  gallons  of  liquor  from  a  higher  density,  D,  to  a  lower 
density,  d.    (See  page  lo7.) 


Lower 

h'lisity, 

ii. 

12. 

11. 

10. 

9. 

8. 

7. 

6. 

5. 

4. 

3. 

2. 

1. 

16 

33-3 

45-1 

60 

77"7 

100 

128-5 

Ifi(r6 

220 

300 

433-3 

700 

1,500 

15 

25-0 

3(i-l 

(".(■.•C) 

87-5 

114-3 

150 

200 

275 

400 

650 

1,400 

11 

l()-(5  27-3 

40 

5  .■)•.") 

75 

100 

133-3 

180 

250 

3(;(;-(; 

600 

1,300 

13 

8-3  H-2 

30 

44-4 

G2-5 

85-7 

116-6 

160 

225 

333-3 

550 

1.200 

12 

9-1 

20 

33-3 

50 

71-4 

100 

140 

2()0 

300 

500 

1,100 

11 

10 

22-2 

37-5 

57-1 

83-3 

120 

175 

266-() 

450 

1,000 

10 

11-1 

25 

42-8 

66-6 

100 

150 

233-3 

400 

000 

9 

12-5 

28-5 

50 

80 

125 

200 

350 

800 

8 

14-2 

33-3 

60 

100 

166-6 

300 

700 

7 

16-6 

40 

75 

133-3 

250 

600 

6 

20 

5(1 

100 

200 

500 

5 

25 

66-6 

150 

400 

4 

33-3 

100 

300 

Anticlilors. — The  residues  of  chlorine  which  may  be  left 
in  pulp  after  bleaching  are  frequently  neutralised  by  the 
use  of  substances  termed  antichlors,  which  react  with  the 
calcium  hypochlorite,  converting  it  into  chlorides. 

The  sodium  hyposulphite  is  the  most  frequently  used 

M  2 


164 


THE  MANUFACTUEE  OE  PAPER 


antichlor,  the  reaction  between  this  and  hypochlorite 
resulting  in  the  formation  of  calcium  sulphate  and  sodium 
chloride  ;  100  lbs.  of  commercial  bleaching  powder  will 
require  30  lbs.  of  crystallised  sodium  hyposulphite. 

The  sulphites  of  soda  and  lime  also  act  as  antichlors, 
reducing  the  hypochlorite  of  calcium  into  sulphate  of  lime 
or  soda.  The  chief  advantage  of  the  use  of  sulphites  is  to 
be  found  in  the  fact  that  the  substances  obtained  by  the 
reaction  are  neutral. 

The  best  practice  in  bleaching  is  to  avoid  the  necessity 
for  using  any  forms  of  antichlors  by  careful  regulation  of  the 
bleaching  process.  It  has  already  been  suggested  in  previous 
references  to  bleaching  that  the  desired  results  are  obtained 
when  the  pulp  and  bleach  are  left  in  contact  with  one 
another  in  tanks  or  drainers  until  the  bleach  is  completely 
exhausted,  the  residual  salts  in  solution  being  removed  by 
thorough  washing. 

Gelatine. — For  animal-sized  or  tub-sized  papers  gelatine 
is  used.  It  can  be  prepared  by  the  paper-maker  from  hide 
clippings,  sheep  skins,  bone,  etc.,  or  can  be  purchased 
ready  made. 

Beadle  gives  the  following  interesting  details  as  to  the 
amount  of  gelatine  which  can  be  obtained  from  wet  hide 
pieces  : — 

Weight  oe  Wet  Hide  Pieces,  2,128  lbs. 


Per  cent. 

Weight  of 

Draught. 

Gallons. 

Gelatine  in 

Gelatine. 

Solution . 

Lbs. 

1 

126-48 

6-775 

85-64 

2 

128-96 

6-052 

78-04 

3  and  4  mixed 

135-20 

9-446 

127-63 

Total  .. 

390-64 

291-31 

Percentage  of  gelatine  on  weight  of  wet  skins  =  13*69. 


CHEMICALS  USED  IN  PAPEE-MAKING  165 


A  similar  trial  on  the  same  class  of  wet  hide  pieces  gave 
a  yield  of  13*23  per  cent. 

Two  trials,  of  a  somewhat  different  class  of  wet  hide 
pieces,  gave  respectively  13-11  and  12*8  per  cent. 

The  temperature  of  the  draught  water  should  be  approxi- 
mately as  follows  : — 


Dranglit. 

At  Begi 

lining. 

At  E 

nd. 

1 

120° 

F. 

150° 

F. 

130° 

F. 

160° 

F. 

3  and  4 

140° 

F. 

180° 

F. 

In  the  final  draught  it  is  often  necessary  to  use  live 
steam  at  the  finish,  but  this  should  be  avoided  if  possible. 

The  water  contained  in  wet  hide  pieces  varies  from  77  to 
90  per  cent,  in  the  different  pieces,  but  in  the  bulk  the 
average  may  be  taken  at  85  per  cent. 

Casein. — Casein  is  the  nitrogenous  principle  of  milk,  and 
belongs  to  the  class  of  proteids  which  are  definite  com- 
pounds of  oxygen,  hydrogen,  carbon,  and  nitrogen,  forming 
the  basis  of  the  most  important  constituents  of  all  animal 
fibres,  albumen,  casein,  and  gluten.  A  very  pure  form 
of  casein  is  cheese  made  fi'om  skimmed  milk.  Casein 
belongs  to  that  class  of  albumens  which  are  soluble  in 
water,  e.g.,  egg  albumen,  blood  albumen  or  serum,  and 
lactalbumen,  or  milk  albumen ;  these  are  mostly  precipi- 
tated from  solution  by  saturation  with  sodium  chloride 
(common  salt)  or  magnesium  sulphate ;  but  they  are  all 
coagulated  by  heat. 

By  the  action  of  rennet  on  milk  the  proteid  or  albumen 
principle  is  converted  into  a  curd  (casein).  This  curd, 
when  freed  from  fats,  is  insoluble  in  water,  but  is  soluble 
in  dilute  acids,  or  alkalies,  or  alkaline  carbonates,  from 


166 


THE  MANUFACTUEE  OE  PAPER 


which  substances,  however,  it  is  reprecipitated  by  acidula- 
tion.  Instead  of  the  above  method,  casein  may  be  pre- 
cipitated from  milk  by  saturation  with  sulphate  of  magnesia, 
and  washing  the  precipitate  with  a  solution  of  that  salt 
until  the  washings  contain  no  albumen,  and  then  redissolv- 
ing  the  prepared  casein  by  adding  water.  The  salt  still 
adhering  to  the  precipitate  enables  it  to  dissolve.  On  a 
large  scale  the  casein  is  usually  prepared  by  treating  the 
milk  with  acid. 

Casein  is  readily  dissolved  by  alkalies  and  alkaline 
carbonates,  borax,  boracic  acid  solution,  caustic  soda,  and 
bicarbonate  of  soda. 

Starch. — This  substance  is  used  in  many  classes  of  paper 
for  improving  the  surface  and  finish.  It  is  added  to  the 
pulp  in  the  beating  engine  in  the  dry  form  as  powder,  or 
in  the  form  of  starch  paste,  produced  by  boiling  the  starch 
in  water. 

The  viscosity  of  the  starch  paste  is  somewhat  increased 
by  the  addition  of  a  small  quantity  of  alkali,  but  due  care 
must  be  exercised  in  boiling,  which  should  only  be  carried 
out  sufficiently  to  cause  the  starch  granules  to  burst,  as 
any  excessive  boiling  causes  the  starch  paste  to  lose  some 
of  its  viscosity,  v 

The  presence  of  starch  in  paper  is  detected  by  the  blue 
colol'ation  produced  when  the  paper  is  dipped  in^o  a  weak 
solution  of  iodine.  The  determination  of  the  exact  per- 
centage of  starch  in  a  paper  is  a  matter  of  some  difficulty. 

Silicate  of  Soda. — Tbe  precipitation  of  gelatinous  silica 
upon  the  pulp  in  the  beating  engine  is  generall}^  regarded 
as  favourable  to  the  production  of  a  sheet  of  paper  having 
what  is  known  as  a  harder  finish.  The  j^i'ecipitation  is 
effected  by  adding  a  solution  of  silicate  of  soda  to  the  beat- 
ing engine,  with  the  subsequent  addition  of  sufficient 
sulphate  of  alumina  to  react  with  the  silicate  of  soda. 


CHEMICALS  USED  IN  PAPEE-MAKING  IB- 


Analysis  OF  Commercial  Alums, 


(Griffin  and  Little.) 


(1) 

(2) 

(3) 

(4) 

Insoluble  in  water 

Alumina  (AI2  0^)  .... 

Iron  protoxide  (Pe  0)  . 

Iron  sesquioxide  (  Fe.2  0^) 

Zinc  oxide  (Zn  0)  . 

Soda(Na2  0)  .... 

Magnesia  (Mg  0)  . 

Sulphuric  acid  (SO3)  combined 

Ill U-LiU-i ciL/ivi  I  k^vyjj  I  liC/t;          •  • 

Water  by  difference 

005 
15-47 
0()2 

ooo 

1-72 
37-26 
45-48 

10-61 
14-96 
0-13 
1*08 

0-57 

37-36 
1  -OS 
34-21 

0-11 
11-64 

0-  06 

1-  17 

4-  75 
0-45 

35-98 

5-  13 
40-71 

0-56 
16-58 

0*04 

0-56 

39-17 

43-09 

100-00 

100-00 

100-00 

100  00 

Sizing  test  (parts  of  dry  neutral 
rosin  size  precipitated  by  one 
part  of  the  alum) 

3-32 

3-47 

3-19 

3-71 

Table  showing  Yalue  of  Solutions  of  Aluminium  Sulphate. 


Pounds  per  100  gallons. 


Pounds  per  100  gallons. 


Twaddel 

A1.2  Oh. 

Sulphate  of 
Alumina 
containing  If)  per 
cent.  AI2  O^. 

Twaddel 

AI2  O3. 

Sulphate  of 
Alumina 
containing  15  per 
cent.  AI2  O3. 

1 

1-4 

■3-4 

9-0 

14 

20-3 

47-3 

135-0 

2 

2-8 

6-5 

19-0 

16 

23-1 

53-8 

155-0 

3 

4-2 

9-8 

28-0 

18 

26-2 

60-3 

172-0 

4 

5-6 

13-0 

37-0 

20 

29-4 

68-5 

196-0 

5 

70 

16-3 

47-0 

25 

37-1 

86-5 

247-0 

6 

8-4 

19-6 

56-0 

30 

44-8 

104-4 

299  0 

7 

9-8 

22-8 

65-0 

35 

53-2 

124-0 

355-0 

8 

11-2 

26-1 

75-0 

40 

60-9 

142-0 

405  0 

9 

12-6 

29-4 

84-0 

45 

68-6 

159-9 

456-0 

10 

14-0 

32-6 

93-0 

50 

77-7 

181-0 

578-0 

11 

15-4 

35-9 

103-0 

55 

86-1 

200-6 

575-0 

12 

16-8 

39-1 

112-0 

60 

95-2 

221-8 

635-0 

168 


THE  MANUFACTUEE  OF  PAPER 


Ahun. — Alum  is  one  of  the  most  im23ortant  substances 
required  in  the  manufacture  of  paper,  its  chief  function 
relating  to  the  sizing  of  paper.  Various  forms  are  utilised 
for  this  purpose,  the  purest  being  sulphate  of  alumina, 
required  for  high  grade  papers,  and  the  cheaper  form 
known  as  alum  cake,  for  news  and  common  printing. 

The  alum  is  manufactured  on  a  large  scale  by  heating 
china  clay  or  bauxite  with  sulphuric  acid.  This  reaction 
gives  sulphate  of  alumina  together  with  silica.  If  the  mass 
is  heated  to  dryness,  it  is  sold  under  the  name  of  alum  cake. 
If  the  mass  is  extracted  with  hot  water  and  the  insoluble 
silica  filtered  off,  the  solution  can  be  evaporated  down  for 
the  production  of  sulphate  of  alumina,  which  is  sold  in  the 
form  of  large  cakes  or  in  the  form  of  crystals. 

By  careful  selection  of  raw  material  a  sulphate  of 
alumina  can  be  prepared  almost  entirely  free  from  iron. 
The  presence  of  the  latter  is  undesirable,  since  on  exposure 
to  air  the  sulphate  of  iron  produced  during  the  manufacture 
of  the  alum  is  slowly  oxidised  and  turns  brown.  Ultimately 
this  affects  the  colour  of  the  finished  paper. 

Alum  is  added  to  solutions  of  animal  size  or  gelatine  in 
order  to  thicken  the  solution  and  render  it  more  viscous. 
It  also  acts  as  a  preservative,  and  is  used  for  regulating  the 
absorption  of  the  gelatine  by  the  paper,  the  penetration 
effects  being  materially  varied  by  the  extent  to  which  the 
alum  is  utilised. 

In  the  process  of  engine  sizing,  a  term  applied  to  the 
application  of  rosin  size  on  account  of  the  fact  that  the 
process  is  comjDieted  in  the  beating  engine,  alum  plays  an 
important  part.  The  mere  addition  of  the  prepared  rosin 
soap  to  the  mixture  of  pulp  and  water  in  the  beating  engine 
does  not  size  the  paper,  but  the  alum  preci|)itates  the  rosin 
from  its  solution,  producing  a  complex  mixture  said  to 
consist  of  resinate  of  alumina  and  free  rosin  particles,  and 


CHEMICALS  USED  IN  PAPER-MAKING  169 


subsequently  the  heat  of  the  i:)aper  machine  drying  cylin- 
ders renders  the  paper  more  or  less  impermeable  to 
moisture. 

The  appearance  and  tone  of  paper,  more  particularly  of 
coloured  papers,  are  brightened  by  the  use  of  an  excess  of 
alum  over  and  above  that  necessary  to  precipitate  the  rosin 
soap. 

Rosin  Size. — This  substance  is  used  chiefly  for  the  sizing 
of  news  and  cheap  printing  papers,  and  is  also  employed 
together  with  gelatine  for  the  commoner  writing  papers. 
It  is  prepared  by  boiling  rosin  with  carbonate  of  soda 
under  various  conditions. 

Rosin,  sometimes  called  colophony,  is  obtained  from  the 
sap  of  certain  firs  and  pine  trees.  This  on  distillation 
yields  spirits  of  turpentine,  leaving  behind  as  a  residue  the 
mixture  of  substances  to  which  is  given  the  name  rosin. 
It  behaves  as  an  acid,  and  therefore  will  combine  with 
certain  alkaline  oxides,  producing  soluble  resinates. 

The  nature  of  the  rosin  soap  used  in  the  paper  mill 
varies  according  to  the  conditions  under  which  the  size  is 
prepared.  If  a  large  proportion  of  rosin  is  used,  then  the 
size  obtained  consists  of  a  mixture  of  resinate  of  soda 
together  with  free  rosin  dissolved  in  the  solution.  If  the 
proportion  of  rosin  is  small  compared  with  the  amount  of 
carbonate  of  soda,  the  composition  of  the  final  mixture  is 
quite  different.  The  difference  in  treatment  results  in  the 
formation  of — 

{A)  Neutral  Size,  prepared  by  boiling  a  known  weight  of 
rosin  with  sufficient  alkali  to  combine  with  it  and  form  a 
neutral  resinate  of  soda.  Theoretically  this  may  be  obtained 
by  using  630  parts  of  rosin  to  100  parts  of  soda  ash.  It  is 
doubtful  how  far  the  reaction  is  completed  so  as  to  produce 
an  exactly  neutral  solution  containing  only  resinate  of 
soda. 


170 


THE  MANUFACTURE  OF  PAPER 


(B)  Acid  Size. — When  the  proportion  of  rosin  is  largely 
increased  the  soda  becomes  converted  into  the  alkaline 
resinate,  and  the  excess  of  rosin  is  gradually  dissolved  in 
the  resinate  formed. 

The  practical  operations  necessary  for  the  preparation  of 
the  size  are  comparatively  simple.  In  the  case  of  size 
containing  relatively  small  percentages  of  free  rosin,  the 
boiling  is  conducted  in  open  vessels,  but  for  the  manufac- 
ture of  rosin  size  containing  large  propol'tions  of  free  rosin 
boiling  under  pressure  in  closed  vessels  must  be  resorted  to. 

With  the  open  pan  process  a  steam  jacketed  pan  is  used, 
and  the  required  quantity  of  alkali,  dissolved  in  water,  is 
placed  therein  and  heated  to  boiling  point.  The  rosin  well 
powdered  is  added  in  small  quantities  from  time  to  time, 
this  being  effected  cautiously  in  order  that  the  carbonic 
acid  gas  set  free  during  the  process  may  readily  escape. 
The  rosin  is  generally  completely  saponified  after  four 
or  five  hours'  boiling.  It  is  then  passed  through  strainers 
into  store  tanks,  from  which  it  is  drawn  into  the  beating 
engines  as  required. 

In  the  case  of  rosin  boiled  under  pressure  a  cylindrical 
vessel  provided  with  a  manhole  at  the  top  is  used.  The 
correct  amounts  of  alkali  and  water  are  put  into  the  digester, 
and  also  the  rosin  in  a  powdered  form,  the  digester  being 
fitted  with  a  perforated  plate  placed  about  two  feet  above 
the  bottom  of  the  vessel  in  order  to  prevent  the  rosin 
forming  into  a  hard  mass  at  the  bottom  of  the  digester. 

It  is  possible  in  this  way  to  manufacture  a  thick  size 
containing  30  or  40  per  cent,  of  free  rosin  and  a  compara- 
tively small  proportion  of  water.  Many  paper  mill  firms 
prefer  to  purchase  such  size  ready  made. 

The  most  recent  modification  of  the  ordinary  rosin  size 
is  a  compound  prepared  by  treating  rosin  with  silicate  of 
soda.    This  alkali  dissolves  rosin  readily,  and  the  soap 


CHEMICALS  USED  IN  PAPEE-MAKING  171 


obtained  when  suitably  diluted  with  water  decomposes  in 
the  beating  engine  on  the  addition  of  aluminium  sulphate, 
with  the  precipitation  of  a  gelatinous  siHca  which  assists  in 
hardening  the  paper. 

Bacon  has  patented  a  process  in  w^hich  powdered  rosin 
is  melted  down  with  dry  crystalline  silicate  of  soda.  The 
resultant  product  is  ground  to  a  fine  powder,  which  is  then 
ready  for  use.  It  dissolves  easily  in  water,  and  when 
decomposed  with  the  proper  proportion  of  alum  gives  a 
gelatinous  viscous  mass  said  to  have  excellent  sizing 
properties. 

The  advantages  of  a  dry  powdered  rosin  size  readily 
soluble  in  water  are  obvious. 

Loadiiu/. — The  term  "loading"  is  applied  to  the  various 
substances  which  are  emj^loyed  for  the  purpose,  as  it 
is  commonly  supposed,  of  making  paper  heavy.  But 
china  clay  and  similar  materials  are  not  added  simply 
in  order  to  give  weight  to  the  paper,  since  they  serve  to 
produce  opacity  and  to  improve  the  surface  of  papers 
which  could  not  be  satisfactorily  made  unless  such  materials 
were  used. 

Examinatuni  of  Paper  for  Loadincj. — If  a  piece  of  paper  is 
crumpled  up,  placed  in  a  small  crucible,  and  then  ignited 
until  all  the  carbonaceous  matter  has  been  burnt  off,  a 
residue  is  left  in  the  crucible  which  may  be  white  or 
coloured.  This  is  usually  termed  the  ash  of  the  paper. 
The  amount  of  ash  present  is  determined  by  taking  a 
weighed  quantity  of  paper  and  weighing  the  residue 
obtained.  Special  appHances  can  be  obtained  for  making 
rapid  determinations  of  the  ash  in  paper,  but  for  occasional 
analyses  they  are  not  required. 

China  Clay. — This  is  the  best  known  and  most  commonly 
used  loading.  The  purest  form  of  this  material  is  kaolin, 
a  natural  substance  formed  by  the  gradual  decomposition 


172 


THE  MANUFACTURE  OF  PAPER 


of  felspathic  rocks  arising  from  exposure  to  the  long- 
continued  action  of  air  and  water.  The  clay  occurs  in 
great  abundance  in  Dorset,  Cornwall,  and  Devon,  the 
southern  counties  in  England,  where  the  most  famous 
deposits  are  found. 

The  natural  mineral  is  levigated  with  water,  and  the 
mixture  allowed  to  flow  through  a  series  of  settling  ponds,  so 
that  the  clay  gradually  settles  in  the  form  of  a  fine  deposit. 
The  clay  is  dried  and  packed  in  bags.  Its  value  is  controlled 
largely  by  the  purity  of  its  colour  and  its  freedom  from  grit 
and  sand.  It  is  essentially  a  silicate  of  alumina,  having 
the  approximate  composition — 


The  specific  gravity  of  the  dry  substance  is  2*50. 

It  is  utilised  as  a  loading  in  all  kinds  of  paper,  and  forms 
also  the  main  ingredient  in  the  coating  found  on  ordinary 
art  and  chromo  papers. 

Asli  containiuf/  China  Claij. — In  news,  cheaj)  printings, 
and  common  art  papers  the  ash  almost  invariably  contains 
china  clay.  This  substance  is  insoluble  in  dilute  acids,  but 
is  acted  upon  by  concentrated  sulphuric  acid  when  digested 
for  some  time.  A  simple  test  for  the  presence  of  china 
clay  in  ash  is  the  blue  coloration  which  is  obtained  when 
the  ash  after  being  ignited  is  gradually  heated  with  a  few 
drops  of  solution  of  cobalt  nitrate.  China  clay  can  be 
decomposed  by  fusion  with  carbonate  of  soda  in  a  crucible. 
By  this  means  silicate  of  alumina  is  decomposed,  and  the 
alumina  goes  into  solution,  the  silica  remaining  as  an 


Sihca  (Si  O2) 
Alumina  (AI2  O3) 
Combined  water . 
Moisture  and  impurities 


43-00 
35-00 
10-00 
12-00 


100-00 


CHEMICALS  USED  IN  PAPER-MAKING  173 


insoluble  residue.  The  filtered  solution  is  boiled  with  an 
excess  of  ammonia  which  gives  a  gelatinous  precipitate  of 
aluminium  hydrate. 

Sulphate  of  Lime. — This  compound  is  valued  chiefly  for 
its  brilliancy  of  colour,  being  used  in  high-class  papers.  It 
is  slightly  soluble  in  water,  to  the  extent  of  about  23  lbs.  in 
1,000  gallons,  and  this  fact  must  be  taken  into  account 
when  the  material  is  added  to  the  pulp  in  the  beating 
engine. 

It  occurs  naturally  in  a  variety  of  forms,  such  as  gypsum, 
alabaster,  selenite,  the  first  of  which  when  finely  powdered 
is  sold  to  the  paper-maker  as  gypsum,  powdered  plaster,  and 
under  other  fancy  names. 

It  can  be  prepared  artificially  by  adding  sulphuric  acid  to 
solutions  of  calcium  salts;  and  the  precipitated  product  so 
obtained  is  sold  as  terra  alba,  pearl  hardening,  satinite, 
mineral  white,  etc. 

The  tests  for  sulphate  of  lime  in  paper  ash  are  based  upon 
the  following  reactions  : — 

Calcium  sulphate  is  soluble  in  dilute  hydrochloric  acid. 
The  addition  of  a  few  drops  of  barium  chloride  to  the 
solution  produces  a  dense  heavy  precipitate,  indicating  the 
sulphate.  A  small  quantity  of  ammonium  oxalate  solution 
added  to  another  portion  of  the  dissolved  calcium  salt  pre- 
viously neutralised  with  ammonia  produces  a  precipitate 
and  indicates  calcium. 

A  microscopic  test  of  paper  for  the  presence  of  sulphate 
of  lime  is  based  upon  the  slight  solubility  of  the  salt  in 
water.  The  paper  is  boiled  with  some  distilled  water.  The 
water  is  evaporated  to  a  small  bulk  and  transferred  to  a 
glass  slip,  and  the  gradual  formation  of  characteristic 
sulphate  of  lime  crystals  can  be  seen  by  means  of  the 
microscope  as  the  water  cools  down. 

French  Chalk. — This  material  is  prepared  by  grinding 


174 


THE  MANUFACTURE  OF  PAPER 


talc  into  a  fine  powder,  and  possesses  a  good  colour  and  a 
somewhat  soapy  feel.  It  is  a  silicate  of  magnesia,  having 
the  approximate  composition — 

Silica  (Si  O2)   62-00 

Magnesia  (Mg  0)   33-00 

Water   4-30 

Traces  of  oxides,  etc.        .       .       .       .  O'TO 

100-00 

Other  siHcates  of  magnesia  used  for  paper-making  are 
agalite  and  asbestine,  the  latter  being  a  finely  ground 
asbestos. 

The  composition  of  asbestos  is  approximately — 


Italian. 

Canadian. 

Lime  and  magnesia 

38-0 

33-0 

Silica  ...... 

42  0 

41-0 

Oxides  of  iron  and  alumina  . 

5  0 

12  0 

Total  water  

18  0 

12-0 

Traces  of  soda,  etc. 

2-0 

3-0 

100-00 

100-00 

CHAPTEK  IX 


THE   PROCESS  OF  BEATING 

Introduction. — The  process  of  beatin^i^  has  for  its  object 
the  complete  breaking  down  of  the  bleached  pulp  to  the 
condition  of  single  fibres,  and  the  further  reduction  of  the 
fibres,  when  necessary,  into  smaller  pieces.  The  disinte- 
gration of  the  material  is  essential  for  the  production  of 
a  close  even  sheet  of  paper,  and  the  amount  of  beating 
required  varies  greatly  according  to  the  nature  of  the  raw 
material,  and  the  class  of  paper  to  be  produced. 

The  textile  trade,  on  the  other  hand,  depends  on  a  raw 
material  composed  of  strong  fibres,  or  of  filaments  cha- 
racterised by  great  length,  and  any  processes  of  treatment 
which  tend  to  reduce  the  length  of  such  fibres  are  carefully 
avoided,  and  it  is  therefore  obvious  that  fibres  which  are  of 
no  value  for  textile  purposes  can  be  appropriated  for  paper- 
making. 

Condition  of  Fibres. — The  great  differences  in  the  jDhysical 
characteristics  and  structure  of  the  fibres  employed  for 
paper-making  suggest  that  the  possible  variations  in  the 
final  product  obtained  by  beating  are  very  numerous.  This 
is  a  well-known  fact,  and  it  is  further  to  be  noted  that  this 
mechanical  operation  brings  about  not  merely  alterations 
of  a  physical  order,  but  introduces  some  interesting  and 
important  chemical  changes. 

Of  the  better-known  materials  linen,  with  an  average 
fibre  length  of  28  mm.,  the  structure  of  which  lends  itself 
to  considerable  alteration  by  beating,  is  in  marked  contrast 


176 


THE  MANUFACTUHE  OF  PAPEE 


to  esparto,  the  fibre  length  of  which  is  only  1*5  mm.  If 
the  process  of  beating  a  linen  rag  merely  resulted  in  the 
cutting  of  all  the  fibres  of  28  mm.  long  into  short  fragments 
of  1'5  mm.,  there  would  be  nothing  remarkable  in  it,  but 
the  changes  which  occur  in  reducing  the  long  linen  fibre  to 
1*5  or  2'0  mm.  are  of  a  far  more  important  character  than 
this. 

Early  Methods. — In  the  early  days  of  paper-making  the 
disintegration  of  the  half-stuff  was  effected  by  a  true 
''beating"  process,  the  rags  being  subjected  to  the  action 
of  heavy  stampers,  which  broke  up  the  mass  of  tangled 
fibre  into  a  uniform  pulp.  The  fibres  for  the  most  jDart 
retained  their  maximum  length  in  this  operation,  which 
was  exceedingly  slow  and  tedious,  though  at  tlie  same  time 
giving  a  sheet  of  paper  of  remarkable  strength. 

The  nearest  imitation  of  these  old-time  rag  papers  is  to 
be  seen  in  the  well-known  Japanese  papers,  which  are 
extraordinarily  strong.  Some  of  these  the  writer  has 
examined  in  order  to  determine  the  length  of  the  fibre. 
The  sheets  when  held  up  to  the  light  appear  "  cloudy  "  and 
"  wild  "  owing  to  the  i)resence  of  the  long  fibres,  which  have 
only  been  separated  or  teased  out  by  the  primitive  methods 
of  beating  used,  and  not  completely  disintegrated. 

Conditions  of  Beating. — About  a.d.  1700  there  began  a 
great  epoch  in  the  history  of  paper-making.  With  the 
invention  of  the  Hollander  engine  about  a.d.  1670,  the  pro- 
cess of  disintegration  was  greatly  hastened,  because  it  was 
possible  to  reduce  the  half-stuff  much  more  readily.  The 
substitution  of  the  idea  of  plain  "  beating  "  by  a  principle 
which  combined  the  gradual  isolation  of  the  individual 
fibres  with  a  splitting  up  of  those  fibres  lengthwise  and 
crosswise  was  not  only  an  advantage  in  point  of  economy 
of  time  and  cost,  but  also  a  material  advance  in  the  possi- 
bilities of  greater  variations  in  the  finished  paper. 


THE  PROCESS  OF  BEATING 


177 


The  conditions  of  the  process  of  beating  carried  out  with 
a  Hollander  permit  of  considerable  alteration,  so  that  these 
changes  in  the  fibre  are  not  surprising  when  properly  under- 
stood. In  fact,  it  is  now  conceded  that  a  close  study  of  the 
theory  and  practice  of  beating  is  likely  to  bring  about  still 
more  remarkable  improvements  in  this  important  depart- 
ment of  the  paper-maker's  work.  The  quality  and  character 
of  the  paper  made  may  be  varied  with — 

(1)  The  origin  of  the  raw  material,  e.g.,  rags,  esparto,  or 
wood  ; 

(2)  The  condition  of  the  material,  e.g.,  old  or  new  rags, 
green  or  mature  esparto,  mechanical  or  chemical  wood  pulp  ; 

(3)  The  time  occupied  in  beating,  e.g.,  four  hours  for 
an  ordinary  rag  printing  and  twelve  hours  for  a  rag  parch- 
ment ; 

(4)  The  state  of  the  beater  knives,  e.g.,  sharp  tackle  for 
blottings  and  dull  tackle  for  cartridge  papers  ; 

(5)  The  speed  of  the  beater  roll,  also  its  weight ; 

(6)  The  rate  at  which  the  beater  roll  is  lowered  on  to  the 
bedplate  ; 

(7)  The  temperature  of  the  contents  of  the  engine. 

The  Beater  Roll. — If  the  beater  roll  is  fitted  with  sharp 
knives,  and  this  is  put  down  close  to  the  bedplate  quickly, 
the  fibres  are  cut  up  short,  and  they  do  not  assimilate  the 
water.  If  the  roll  is  fitted  with  dull  knives,  or  "  tackle,"  as  it 
is  sometimes  called,  and  it  is  lowered  gradually,  the  fibres 
are  drawn  and  bruised  out  without  being  greatly  shortened. 
In  this  condition  the  stuff  becomes  very  *'wet,"  or  "greasy," 
as  it  is  termed.  The  cellulose  enters  into  association  \vith 
water  when  beaten  for  many  hours,  and  the  pulp  in  the 
beating  engine  changes  into  a  curious  greasy-like  mass  of 
a  semi-transparent  character.  Eag  pulp  beaten  for  a  long 
time  produces  a  hard,  translucent,  dense  sheet  of  paper. 
Flax  thread  beaten  48  to  60  hours  is  used  in  practice 

p.  N 


178 


THE  MANUFACTURE  OE  PAPER 


for  the  manufacture  of  gramophone  horns  and  similar 
purposes. 

Soft  porous  papers  Hke  blottings,  filtering  papers,  heavy 
chromos,  litho  papers,  antiques,  light  printings,  are  made 
from  pulps  which  are  beaten  quickly  with  the  roll  put  down 
close  to  the  bedplate  soon  after  the  stuff  has  been  filled  in. 

With  strong,  dense,  hard  papers,  such  as  parchments, 
banks,  greaseproofs  and  the  like,  the  pulp  is  beaten  slowly 
and  the  roll  lowered  gradually. 

The  nature  of  the  pulp  and  the  time  occupied  in  beating 
are  also  important  factors  in  producing  these  different 
papers,  three  to  four  hours  being  ample  for  an  ordinary 
wood  pulp  printing,  whereas  a  wood  pulp  parchment 
requires  seven  to  eight  hours. 

Bcatiufi  Pulps  Separately. — The  use  of  esparto  and  wood 
pulp  in  conjunction  with  one  another,  or  blended  with  rag, 
has  introduced  new  problems  into  the  question  of  beating. 
Perhaps  the  most  important  of  these  is  the  advisability  of 
beating  the  pulps  separately  and  eventually  passing  them 
through  a  mixer  of  some  kind  before  discharging  into  a 
stuff  chest.  The  necessity  for  differentiating  the  amount  of 
beating  is  already  partly  recognised  when  very  dissimilar 
pulps,  such  aS  strong  rag  and  esparto,  are  blended,  but  the 
whole  subject  ought  to  be  carefully  studied  by  the  paper- 
maker  and  investigated  on  its  merits  from  the  standpoint 
of  "  beating  effects,"  apart  from  questions  of  cost  and 
expediency.  The  former  fully  understood  and  exhaustively 
examined  by  practical  tests  would  of  course  only  be  de- 
veloped if  proved  to  be  advantageous. 

The  field  of  research  in  this  direction  has  not  yet  been 
seriously  explored.  With  the  enormous  consumption  of 
wood  pulps  of  varying  quality  made  from  many  different 
species  of  wood  by  several  processes,  there  is  ample  room 
for  interesting  and  profitable  enquiry,  particularly  as  the 


THE  PEOCESS  OF  BEATING 


179 


types  of  beating  engine  are  so  numerous.  The  effects 
produced  by  the  Hollander,  the  refiner,  the  edge  runner, 
the  stone  beater  roll,  and  other  mechanisms,  are  all  of 
varying  kinds. 

Effect  of  Peolonged  Beating. 

The  importance  of  a  knowledge  of  the  precise  effects  pro- 
duced by  the  beating  of  pulp  cannot  be  emphasised  too 


Fig.  46. — Cotton  Pulp  beaten  8  hours. 


much,  and  any  contributions  to  the  subject  along  the  lines 
of  special  research  will  be  welcomed  by  all  students  of 
cellulose. 

Some  experiments  were  conducted  by  the  writer  in  1906 
with  cotton  rags,  in  order  to  determine  the  results  obtained 

N  2 


180 


THE  MANUFACTITEE  OF  PAPEE 


by  beating  the  pulp  for  a  prolonged  period  under  exact  and 
specific  conditions. 

The  cotton  rags,  of  good  quality,  were  boiled  with  caustic 
soda  in  the  usual  way  for  six  or  seven  hours,  at  a  pressure 
of  15  to  20  lbs.,  washed  and  partially  broken  down  in  the  rag 


EiG.  47. — Cotton  Palp  beaten  37  hours. 


breaker,  and  finally  bleached,  made  into  half-stuff,  and  then 
transferred  to  a  Hollander  beating  engine. 

The  particular  conditions  specified  for  the  beating  opera- 
tion were  that  the  beaterman  should  manij^ulate  the  j^ulp 
according  to  his  usual  routine  for  the  manufacture  of  the 
pai)er  which  he  was  accustomed  to  make  from  these  rags. 
In  this  case  the  routine  process  meant  beating  for  eight 
hours,  by  which  time  the  pulp  was  ready  for  the  paper 
machine.     In  the  ordinary  course  the  pulp  would  be 


THE  PROCESS  OF  BEATING  181 

discharged  into  the  staff  chest,  and  converted  into  a  strong, 
thin,  bank  paper. 

During  the  prolonged  beating  the  pulp  became  very  soft 
and  greasy,"  and  when  made  up  into  sheets  the  paper  as 
it  dried  exhibited  remarkable  differences  in  shrinkage,  the 
dry  sheets  obtained  from  puljJ  beaten  thirty-seven  hours 
being  much  smaller  than  those  obtained  from  iml]}  beaten 
only  four  or  six  hours.  The  actual  shrinkage  is  shown  in 
the  following  table  : — 


Hours. 

Area  of  Sheet. 
Sq.  mill. 

Loss  of  Area. 
Sq.  mm. 

Relative 
Areas. 
Deckle  100 

iSliiinkaj^e 
per  cent. 

0 

26,384-0 

100-0 

4 

26,07()-() 

308-0 

98-9 

1-1 

6 

25,520-1 

863-9 

96-7 

3-3 

8 

25,l()0-0 

1,224-0 

95-4 

4-6 

10 

24,794-8 

1,589-2 

93-9 

61 

13 

24,467-4 

1,916-6 

92-8 

7-2 

15 

24,215-2 

2,168-8 

91-8 

8-2 

17 

24,0240 

2,360-0 

90-9 

91 

19 

23,616-2 

2,767-8 

89-6 

10-4 

21 

23,616-0 

2,768-0 

89-6 

10-4 

23 

23,535*7 

2,848-3 

89-3 

10-7 

25 

23,329-9 

3,054-1 

88-5 

11-5 

27 

22,920-5 

3,463-5 

86-9 

13-1 

29 

22,831-2 

3,552*8 

86-5 

13-5 

31 

22,492-9 

3,891-1 

85-3 

14-7 

33 

21,917-2 

4,466-8 

83  1 

16-9 

35 

21,226-1 

5,157-9 

80-5 

19-5 

37 

20,778-8 

5,605-2 

78-8 

21-2 

If  these  results  are  plotted  in  the  form  of  a  curve  the 
relation  between  the  period  of  beating  and  the  shrinkage 
in  area  is  clearly  shown.  For  the  first  twenty  hours 
the  shrinkage  is  proportional  to  the  period  of  beating, 
after  which  the  curve  assumes  an  irregular  shape,  show- 
ing a  tendency  for  shrinkage  to  proceed  at  a  faster 
rate. 


182 


THE  MANUFACTUEE  OF  PAPER 


Weight  and  Substance  of  the  Paper. — The  shrinkage  of 
the  paper  after  prolonged  beating  indicates  a  closer  and 
denser  sheet,  so  that  for  papers  of  equal  thickness  the 
weight  per  unit  area  was  much  greater  in  the  case  of  the 
pulp  beaten  for  the  full  period.  The  results  obtained  are 
very  interesting,  and  the  following  summary  for  a  few  of 
the  readings  obtained  will  serve  to  show  the  alteration 
effected. 


Hour.s. 

\Yeight  of 
20,000  sq.  mm. 
Giams. 

Tliickness  of 
mm. 

Grams  per 
S(i.  metre. 

Lbs.  per  ream 
480  ^lleets, 
20"  X  30". 

Class  A 
8-10  In  s. 

l-S7o 

•1S.1 

9;j-7o 

;3s-2;3 

Class  ]>> 
19-21  his. 

2  •043 

•ISO 

102-irj 

41-0,3 

Class  C 

a.'j-ao  hrs. 

2 -20:3 

•  1  (S9 

llO-lc) 

44 -93 

Sizing  and  Glazing  Effects. — The  behaviour  of  the  water- 
leaf  jmper  after  sizing  and  glazing  gave  some  interesting 
results.  In  the  first  place,  the  effect  of  the  altered  density 
of  the  paper  is  strikingly  shown  by  the  amount  of  the  size 
absorbed.  Certain  selected  sheets  were  passed  through  a 
solution  of  ordinary  gelatine  in  the  usual  way,  and  subse- 
quently dried.  The  amount  of  gelatine  absorbed  differs  in 
a  remarkable  degree,  as  shown  in  table. 

Tensile  StrengtJt  of  the  Paper. — It  is  interesting  to  note 
that  the  tensile  strength  of  the  waterleaf  papers  appears  to 
remain  fairly  constant  throughout  the  whole  period  of 
beating.  But  this  uniformity  is  greatly  altered  by  the 
operations  of  sizing  and  glazing. 


THE  PROCESS  OF  BEATING 


183 


Peticentage  of  Air-dry  Gelatine  absorbed  by  the 
Waterleaf  Sheets. 


Hours. 

Percentage  of  Size  absorbed. 

Mean. 

1st  Trial. 

2nd  Trial. 

3rd  Trial. 

8 

5'5 

6-0 

6-2 

5-9 

10 

5-4 

6-8 

6-5 

6-2 

19 

3-8 

5-0 

4-5 

4-4 

21 

4-8 

3-9 

4-6 

4-4 

:rs 

2-7 

1-7 

2-4 

2-3 

35 

2-4 

1-9 

1-7 

2-0 

These  results  are  rather  remarkable.  The  prolonged 
beatiDg  does  not  seem  to  have  affected  the  tensile  strength 
of  the  waterleaf,  and  the  practical  loss  of  strength  which 
actually  occurs  in  the  more  completely  finished  paper  does 
not  manifest  itself  until  after  the  sizing  process.  The 
importance  of  the  gelatine  as  a  factor  in  the  ultimate  strength 
is  thus  clearly  and  strikingly  demonstrated. 

Tests  for  Strength  on  Original  Waterleaf  Paper. 


Hours. 

Mean  result  of 
Readings. 
Lbs. 

Mean  Strength 
ol  the  I'aper. 
Lbs. 

8 

a 

14-1 

12-1 

b 

10-1 

10 

a 

15-4 

13-2 

b 

10-9 

19 

a 

Uro 

14-0 

b 

11-4 

21 

a 

15-2 

14-0 

b 

12-8 

33 

a 

13-4 

12-4 

b 

11-4 

35 

a 

14-5 

13-G 

b 

12-'; 

THE  MANUFACTURE  OF  PAPER 


Tests  tor  Strength  on  Papers,  Sized  only. 


Hours. 

Mean  result  of 
Readings. 
Lbs. 

Mean  Strength 
of  the  Paper. 

T 

8 

a 

22-7 

20-0 

b 

17-3 

10 

a 

28-5 

23-2 

b 

18-0 

19 

a 

22-5 

21-0 

b 

19-5 

21 

a 

26-0 

21-7 

b 

17-5 

33 

■  a 

15-0 

15-0 

b 

15-0 

35 

a 

14-2 

15-3 

b 

16-5 

Tests  for  Strength  on  Paper  Sized  and  Glazed. 


Hours. 

Mean  result  of 
Reailngs. 
Lbs. 

Mean  Strength 
of  the  Paper. 
Lbs. 

^  8 

a 

25-8 

23-6 

b 

21-4 

10 

a 

28-4 

23-6 

b 

18-9 

19 

a 

27-0 

22-9 

b 

18-9 

21 

a 

24-9 

22-7 

b 

20-6 

33 

a 

16-1 

15-2 

b 

14-4 

35 

a 

17-5 

16-2 

b 

15-0 

THE  PEOCESS  OF  BEATING 


185 


It  may  also  be  noticed  that  the  strength  of  the  finished 
paper  after  twenty  hours'  beating,  as  in  class  B,  is  equal  to 
that  of  the  paper  after  nine  hours'  beating,  as  in  class  A. 
This  is  curious,  especially  in  view  of  the  fact  that  the  per- 
centage of  gelatine  in  the  papers  of  class  B.  is  only  4*4  per 
cent,  as  against  6'0  per  cent,  in  class  A. 

The  relation  of  the  percentage  of  gelatine  to  the  period  of 
beating  thus  becomes  a  matter  of  interest,  and  well  worth 


EiG.  48. — Plan  and  Sectional  Elevation  of  a  "  Hollander." 

investigation.  The  figures  are  suggestive  of  further 
experimental  research  along  definite  lines. 

Developments  in  Beating  Engines. — Since  the  introduc- 
tion of  the  Hollander  beating  engine,  about  a.d.  1670,  other 
types  of  beater  almost  too  numerous  to  mention  have  been 
devised  to  supersede  it,  but  the  fact  remains  that  the 
principle  of  the  original  Hollander  and  its  general  design 
are  still  adhered  to  in  the  engines  used  by  paper-makers  for 
high-class  work. 

The  alterations  and  improvements  which  have  taken 


186 


THE  MANUFACTUEE  OF  PAPER 


place  during  the  last  fifty  years  relate  chiefly  to  the  modi- 
fications naturally  arising  from  the  introduction  of  fibres 
not  requiring  such  drastic  treatment  as  rags. 

The  machines  now  in  use  for  reducing  half-stuff  to  beaten 
pulp  ready  for  the  paper  machine  may  be  classified  as 
follows : — 

(1)  Beaters  of  the  Hollander  type,  in  which  the  circula- 
tion of  the  pulp  in  the  engine  and  the  actual  beating  process 


(4)  Refiners,  containing  conical  shaped  beater  rolls 
working  in  a  conical  shell  fitted  with  stationary  knives. 

The  Hollander. — This  beating  engine  in  its  simplest  form 
consists  of  an  oval  shaped  trough,  divided  into  two  channels 
by  a  "  midfeather,"  which  does  not,  however,  reach  com- 
pletely from  one  end  to  the  other. 

In  one  of  the  channels  the  bed  of  the  trough  slopes  up 
slightly  to  the  place  where  the  "  bedplate  "  is  fixed.  The 
bedplate  consists  of  a  number  of  stout  metal  bars  or  knives 
firmly  fastened  into  an  iron  frame,  which  lies  across  this 


are  both  effected  by  the 
beater  roll. 


(2)  Beaters  of  the 
circulator  type,  in  which 
the  movement  of  the 
pulp  is  maintained  by 
a  special  contrivance, 
and  the  beater  roll  used 
only  for  beating. 


Fig.  49. — Beating  Engine  with 
Four  Beater  Rolls. 


(3)  Beaters  of  the 
stone  roll  type  in  which 
the  roll  and  bedplate 
are  either  or  both  com- 
posed of  stone,  granite, 
or  similar  non-metallic 
substance. 


THE  PEOCESS  OF  BEATING 


187 


channel.  The  beater  roll,  a  heavy  cast-iron  roll  provided 
with  projecting  knives  or  blades  arranged  in  clumps  of 
three  around  the  circumference,  and  supported  on  bearings 
at  each  side  of  the  engine,  revolves  above  the  bedplate  with 
the  knives  adjusted  to  any  required  distance  from  it,  the 
raising  or  lowering  of  the  beater  roll  for  this  purpose  being 
effected  by  the  use  of  adjustable  bearings. 

The  bed  of  the  trough  behind  the  beater  roll  rises  sharply 
up  from  the  bedplate  and  then  falls  away  suddenly,  as 
shown  in  the  diagram,  forming  the  "  backfall." 

When  the  engine  is  in  operation  the  mixture  of  water 
and  pulp  is  drawn  between  the  knives  and  circulated  round 
the  trough.  The  material  is  disintegrated  into  fibres  of 
the  required  condition,  discharged  over  the  backfall,  and 
kept  in  a  state  of  continual  circulation,  and  the  beating 
maintained  until  the  stuff  has  been  sufficiently  treated. 

The  dimensions  of  the  engine  vary  according  to  the 
capacity,  which  is  usually  expressed  in  terms  of  the  amount 
of  dry  pulp  the  beater  will  hold,  and  the  following  figures 
may  be  taken  as  giving  the  average  sizes : — 


2  cwt.  Engine. 

5  ewt.  Engine. 

Length . 
Width  . 

Depth  (average)  . 
Diameter  of  roll  . 

1 1  ft.  0  in. 
5  ft.  6  in. 

2  ft.  3  in. 

3  ft.  6  in. 

16ft.  Oin. 
8  ft.  0  in. 

2  ft.  9  in. 

3  ft.  6  in. 

Sundry  modifications  in  the  form  and  arrangement  of  the 
beater  have  been  tried  from  time  to  time.  In  1869  Granville 
patented  the  substitution  of  a  second  beater  roll  in  place  of 
the  stationary  bedplate  for  the  purpose  of  hastening  the 
operation.  Repeated  attempts  have  been  made  to  construct 
a  beating  engine  with  two  or  more  rolls,  but  it  is  evident 
that  such  a  device  could  hardly  succeed,  since  it  would  be 


188 


THE  MANUFACTUEE  OF  PAPEE 


impossible  to  ensure  proper  adjustment  of  the  rolls,  and  in 
that  case  one  roll  might  be  doing  all  the  work. 

The  first  machine  of  this  type  was  patented  in  1872  by 
Salt.  Similar  beaters  were  devised  by  Forbes  in  1880, 
Macfarlane  in  1886,  Pickles  in  1894,  who  proposed  to  use 
three  rolls,  and  Partington  in  1901.  Hoffman  describes  a 
beating  engine  which  was  working  in  America  containing 
four  rolls,  as  shown  in  the  diagram. 

llie  Umpherston. — A  notable  modification  of  the  Hollander, 
having  an  arrangement  by  which  the  two  channels  of  the 


Fig.  50. — Umplierston  Beater. 


engines  are  placed  under  one  another,  and  one  which  is 
largely  used  for  fibres,  is  the  Umpherston.  Several  engines 
differing  in  detail,  but  embodying  the  same  principle,  have 
been  built  in  imitation  of  this  one. 

Bedplates  of  large  working  surface  were  first  tried  in 
England  by  Cooke  and  Hibbert,  in  1878,  but  in  practice 
it  has  been  found  that  no  serious  deviations  from  the  narrow 
type  of  plate  are  of  much  value.  As  a  matter  of  fact  it  is 
held  by  some  paper-makers  that  one  or  two  knives  would  be 
sufficient  if  they  could  be  relied  on  to  keep  true  and  in 
proper  adjustment. 


THE  PEOCESS  OF  BEATING 


189 


The  Circulating  Type  of  Beater. — The  addition  of  some 
device  for  keeping  the  pulp  in  circulation  apart  from  the 
action  of  the  roll  has  received  considerable  attention.  The 
early  experiments  in  this  direction  with  the  Hollander  led 
ultimately  to  the  construction  of  the  engine  of  the  circulator 
type  mentioned  in  class  2. 

Thus,  in  1872,  Nugent  patented  a  special  paddle  to  be 
used  in  the  Hollander,  by  which  the  pulp  in  the  trough  of 
the  beater  was  impelled  towards  the  roll.  Many  other  plans 


Fig.  51. — Section  of  Unipherston  Beating 
Engine. 


were  tried  for  this  purpose,  and  details  can  be  seen  in  the 
List  of  Patents  (see  page  192). 

The  introduction  of  the  beaters  with  special  means  of 
circulating  the  pulp  was  found  to  be  of  the  greatest  service 
in  the  treatment  of  stuff  like  esparto  and  wood  pulp,  since 
these  materials  did  not  require  the  drastic  measures  neces- 
sary with  rag  pulp.  In  1890  several  engines  of  this  class 
were  being  adopted,  amongst  which  may  be  mentioned 
Hemmer's,  Eeed's  and  Taylor's.  The  pulp  discharged  from 
the  beater  roll  was  drawn  through  an  independent  pipe 
or  channel  by  means  of  an  Archimedean  screwy  or  a 
centrifugal  pump. 

Stone  Beater  Bolls. — The  substitution  of  stone  for  metal 
in  the  roll  and  bedplate  of  the  engine  brings  about  some 


190 


THE  MANUFACTURE  OF  PAPER 


remarkable  changes  in  the  nature  of  the  beaten  stuff.  The 
fibre  is  submitted  to  the  action  of  rough  surfaces  rather 
than  that  due  to  the  contact  of  sharp  edges,  with  the  result 
that  the  disintegration  is  much  more  rapid,  and  produces  a 
"  wet  "  working  pulp  suitable  for  imitation  parchments  and 
similar  papers.    The  latest  materials  used  for  this  purpose 


EiG.  52. — Nugeut's  Beatiug  Engine  with  Paddles  for  Circulating 
the  Pulp. 

are  basalt  lava  stone  in  Germany,  and  carborundum  in 
America. 

Care  is  necessary  in  the  manipulation  of  these  beaters  to 
prevent  fracture  of  the  stone  parts.  In  the  Wagg  Jordan 
engine  this  danger  is  materially  reduced  by  the  construction 
of  the  working  parts. 

Refiners. — In  these  engines  the  beater  roll  is  a  conical 
shaped  drum  carrying  the  knives,  which  revolve  inside 
a  conical  shell  completely  lined  with  fixed  knives.  The 
fibres  are  thus  cut  up  to  the  desired  length,  but  before  dis- 
charge from  the  engine  they  pass  between  two  circular  discs, 


THE  PEOCESS  OF  BEATING 


191 


one  stationary  and  the  other  revolving  in  a  vertical  position. 
The  effect  of  the  discs  is  to  tear  or  bruise  the  fibres  rather 
than  to  cut  them. 

The  refiner  is 
best  employed  to 
clear  or  brush  out 
the  mass  of  pulp 
after  a  certain 
amount  of  prelimi- 
nary treatment  in 
the  beater,  as  the 
refiner  cannot  pro- 
duce the  effects 
obtained  by  actual 
beating  as  in  the 
Hollander. 

Power  Consump- 
tion. —  The  long 
treatment  required 
to  thoroughly  pulp 
a  strong  material 
demands  a  great 
amount  of  power. 
Engines  differ  con- 
siderably in  their 
power  consump- 
tion, and  compari- 
sons are  frequently 
made  in  terms  of 
the  power  required 
to  beat  a  given 
weight    of  pulp. 

But  this  is  not  always  a  true  criterion  of  efficient  work. 
Some  types  of  beater  are  suitable  for  producing  certain 


Fig.  53. — A  "Tower"  Beating  Engine  with 
Centrifugal  Pump  for  Circulating  Pulp. 


192 


THE  MANUFACTURE  OF  PAPER 


results,  and  the  mere  substitution  of  a  beater  consuming 
less  power  is  worse  than  useless  unless  it  can  be  shown  that 
the  same  effects  are  being  obtained.  The  efficiency  of  the 
Hollander  for  the  beating  of  rag  pulp,  in  spite  of  the  high 
power  consumption,  is  a  case  in  point. 

With  this  factor  properly  considered,  the  power  required 


Fig.  o4. — Working  Parts  of  a  Modern  Refining  Engine. 

for  beating  becomes  an  interesting  study.  Many  detailed 
experiments  have  been  published  from  time  to  time,  the 
most  recent  being  those  described  by  Beadle. 

Patents  taken  out  in  Connection  with  Beating 
Engines. 

1855.  Park  (1170). — A  small  steam  engine  was"^  attached 
to  the  shaft  of  the  beater  roll,  so  that  it  could  be  driven  direct. 


BEATING  ENGINES 


193 


1856.  KiNGSLAND  (2828). — A  form  of  refiner  in  which  the 
pulp  was  beaten  by  a  vertical  disc  rotating  in  an  enclosed 
case. 

1860.  Jordan  (792). — A  machine  devised  for  mixing  size 
with  pulp,  made  like  a  conical  refining  engine,  the  rubbing 
surface  being  provided  with  teeth  or  cutters. 

1860.  Jordan  (2019).  —  An  engine  of  the  refiner  type, 
constructed  with  a  conical  drum  rotating  in  a  conical 
casing.  The  knives  at  the  larger  end  of  the  drum  are 
placed  closer  together  than  those  on  the  smaller  end. 

1863.  Park  (1138).^ — Two  beaters  placed  side  by  side  are 
driven  by  one  steam  engine  placed  between  them,  the 
operations  being  so  timed  that  one  rag  engine  is  used  for 
breaking  while  the  other  is  finishing. 

1864.  Ibotson  (2913). — The  23ulp  is  passed  continuously 
from  one  engine  roll  to  another,  or  from  one  part  of  a 
beater  roll  to  another  part  of  the  same  roll  through  slotted 
plates. 

1866.  KoECKNER  (140). — A  beating  engine  of  the  refiner 
type  with  conical  drum  and  casing. 

1866.  Berham  (3299). — A  beating  engine  of  the  conical 
type  with  the  beater  roll  rotating  vertically  instead  of 
horizontally. 

1867.  Crompton  (482). — Device  for  raising  the  bars  in 
the  beater  roll  as  the  edge  of  the  plate  wears  away. 

1867.  Wood  (914). — Modification  in  the  form  of  the  beater 
bars  (of  little  importance). 

1867.  Edge  (3673).— The  knives  of  the  beater  roll  dis- 
tributed at  equal  distances  apart  all  round  the  roll,  alternated 
with  strips  of  wood. 

1869.  Granville  (1041). — Substitution  of  a  second  beater 
roll  for  the  stationary  bed-plate,  the  knives  being  set  spirally 
round  the  roller. 

1869.  Newell  (2905). — Weight  of  the  beater  roll  counter- 

p.  o 


194 


THE  MANUFACTtJEE  OE  PAPER 


poised  to  allow  of  the  exact  regulation  of  the  pressure  on  the 
stuff  in  the  beating  engine. 

1870.  EosE  (997).  —  An  intercepting  plate  fixed  to  the 
cover  of  the  beating  engine  which  causes  that  part  of  the 
stuff  which  was  usually  carried  right  round  by  the  roll  to  fall 
back  behind  the  backfall. 

1870.  Bentleyand  Jackson  (1633) — A  beater  roll  having 
the  same  width  as  the  engine,  and  provided  with  a  cover 
fitted  with  a  pipe  which  conducted  the  material  back  to  the 
front  of  the  roll. 

1871.  Patton  (1336). — Bottom  of  beating  engine  curved 
in  order  to  prevent  the  stuff  settling  or  accumulating  at  any 
portion  of  the  machine. 

1872.  Salt  (1901). — A  beating  engine  of  usual  type,  but 
having  two  beater  rolls  and  two  drum  washers,  one  pair  in 
each  of  the  two  channels. 

1873.  Gould  (769). — A  curious  engine  with  horizontal 
shaft  having  a  circular  disc  at  the  lower  end,  fitted  with 
knives  on  the  under- surface,  which  are  in  contact  with  fixed 
knives  lying  at  the  bottom  of  the  vessel.  The  circulation 
of  the  pulp  is  effected  by  the  centrifugal  force  generated. 

1873.  Martin  (3751). — A  beating  engine  with  two  rolls 
in  the  same  trough,  the  first  roll  working  in  conjunction 
with  a  smooth  surfaced  beating  roll,  the  other  being  in 
contact  with  a  bedplate  of  the  usual  type,  the  object  of  the 
first  roll  being  to  partially  disintegrate  the  material  without 
danger  of  choking. 

1874.  Johnstone  (3708). — A  pulping  engine  in  which 
the  rubbing  action  of  two  grindstones  one  upon  the  other  is 
utilised  as  a  means  of  beating. 

1876.  Gardner  (307).  —  A  beating  engine  in  which  the 
beater  roll  is  conical  in  shape,  working  vertically  in  contact 
with  the  bottom  of  the  beating  engine,  which  is  also  conical 
in  shape,  the  engine  itself  being  circular. 


BEATING  ENGINES 


195 


1878.  Cooke  and  Hibbert  (4068).  —  The  bedplate  con- 
structed in  the  form  of  a  circular  segment  with  a  much 
larger  face  than  usual,  and  capable  of  adjustment,  the 
beater  roll  itself  being  fixed  in  the  bearings. 

1880.  Forbes  (692). — A  long  oval  shaped  beating  engine 
divided  into  three  channels  instead  of  two.  In  the  two 
outer  channels  are  placed  beater  rolls  and  drum  washers. 
The  stuff  discharged  over  the  backfalls  from  the  two  beat- 
ing engines  flows  down  the  central  channel  and  is  circulated 
by  a  special  paddle  constructed  in  such  a  manner  as  to 
deliver  the  pulp  in  two  equal  streams  into  the  outer  channels 
to  each  of  the  beater  rolls. 

1880.  Umpherston  (1150). — An  engine  constructed  with 
a  passage  below  the  backfall  so  that  the  stuff  circulates 
in  a  trough  underneath  the  beater  roll,  the  object  being  to 
ensure  more  effective  treatment  and  to  save  floor  space. 

1883.  AiTCHisoN  (5381).  —  A  beating  engine  of  usual 
form,  but  with  the  beater  roll  made  conical  in  shape  with 
the  larger  circumf3rence  outwards,  and  the  bedi)late  placed 
on  an  incline  parallel  with  the  knives  on  the  beater  roll. 

1884.  Mayfield  (2028).— The  backfall  of  the  beating 
engine  is  of  entirely  different  construction  to  the  ordinary 
machine,  for  the  purpose  of  improving  the  circulation. 

1884.  HoYT  (11177). — An  engine  resembling  the  Um- 
pherston, but  with  a  larger  roll,  the  diameter  of  which 
is  equal  to  the  full  depth  of  the  engine,  the  backfall  being 
in  a  line  with  the  axis  of  the  beater  roll. 

1885.  Jordan  (7156). — Additions  to  the  Jordan  engine 
for  admitting  water  and  steam  to  the  engine  as  required. 

1885.  KoRSCHiLGEN  (9433). — The  beater  roll  made  of 
stone  or  of  metal  with  a  stone  casing  furnished  with  ribs 
or  knives  placed  close  together. 

1886.  Hibbert  (4237). — A  beating  engine  fitted  with  an 
ordinary  beater  roll,  and  having  in  addition  a  heavy  disc 

o  2 

1 


THE  MANUFACTUEE  OF  PAPER 


rotating  vertically,  the  disc  being  fitted  with  knives  on  one 
surface  which  rotate  in  contact  with  knives  fixed  on  a 
stationary  disc. 

1886.  Kron  (9885). — A  device  for  securing  better  circula- 
tion of  the  pulp,  the  stuff  leaving  the  beater  roll  being 
divided  into  two  streams  which  are  brought  together  again 
in  front  of  the  roll. 

1886.  HoRNE  (10237). — A  long  rectangular  vessel  with  a 
large  beater  roll  at  one  end,  contrived  so  as  to  force  the  pulp 
leaving  the  beater  roll  to  pass  down  a  partition  separating 
it  from  the  pulp  going  towards  the  beater  roll. 

1886.  Macfarlane  (11084). — An  engine  fitted  with  two 
beater  rolls  which  rotate  in  opposite  directions,  the  stuff 
being  mixed  between  them. 

1887.  Nacke  (746). — A  centrifugal  circulating  wheel 
rotating  horizontally  in  the  centre  of  the  beating  engine  is 
used  in  combination  with  a  parallel  cutting  disc. 

1887.  Marshall  (1808). — A  conical  refiner  having  in 
addition  at  its  large  end  a  pair  of  grinding  discs  fitted  with 
knives  and  rotating  vertically. 

1887.  VoiTH  (6174). — An  alteration  to  the  covers  of  the 
beater  rolls  which  prevent  stuff  from  being  carried  round 
the  cylinder,  and  cause  it  to  pass  over  the  backfall  freely. 

1890.  Hemmer  (17483). — A  beating  engine  provided  with 
a  separate  return  channel  for  the  pulp,  the  circulation 
through  the  channel  being  effected  by  a  small  centrifugal 
pump. 

1890.  A.  E.  KiiED  (19107).— A  beating  engine  in  which 
the  pulp  discharged  over  the  backfall  is  delivered  to  the 
front  of  the  beater  roll  by  a  screw  propeller. 

1891.  Karger  (11564). — A  beater  similar  to  the  Umpher- 
ston,  but  provided  with  a  circulating  roll  fitted  with  radial 
projections  which  delivers  the  stuff  to  the  front  of  the  beater 
roll. 


BEATING  ENGINES 


197 


1892.  Taylor  (7397). — A  beating  engine  in  which  the 
beater  roll  operates  in  a  closed  chamber  above  the  vat  full 
of  pulp,  the  stuff  being  continually  circulated  by  a  centri- 
fugal pump  which  draws  the  stock  from  the  bottom  of  the 
vat  and  delivers  it  to  the  beater  roll. 

1892.  Annandale  (9173).  —  A  conical- shaped  beating 
engine  with  the  beater  roll  rotating  in  a  vertical  position, 
the  larger  end  of  the  cone  being  downwards. 

1892.  Umpherston  (15766). — An  addition  to  the  beating 
engine  arranged  so  that  two  fixed  bedplates  are  used 
instead  of  one. 

1892.  Miller  (15947). — A  machine  in  which  two  fixed 
bedplates  are  used,  one  below  the  beater  roll  and  one  above, 
the  engine  being  fitted  with  suitable  bafiie  plates  to  ensure 
I)roper  circulation. 

1893.  Pearson  and  Bertram  (11956). — A  special  form  of 
refining  engine  in  which  the  pulp  is  subjected  to  the  action 
of  discs  rotating  vertically,  the  knives  being  arranged 
radially  on  the  disc. 

1893.  Caldwell  (15332). — A  rotary  beating  engine  in 
which  the  beating  surfaces  admit  of  accurate  adjustment. 

1894.  CoRNETT  (945). — An  outlet  is  fixed  to  the  beater 
roll  casing  close  to  the  discharge  from  the  bedplate,  so  that  the 
roll  is  not  impeded  by  the  weight  of  the  pulp,  which  is 
subsequently  pumped  to  the  front  of  the  beater  roll. 

1894.  Shand  AND  Bertram  (4136). — A  beating  engine 
similiar  to  the  Umpherston  beater  in  which  the  beater  roll 
is  raised  up  out  of  the  pulp  and  the  circulation  effected  by 
means  of  a  worm  which  delivers  the  pulp  to  the  front  of  the 
beater  roll. 

1894.  Pickles  (20255). — A  beating  engine  somewhat 
similar  to  an  Umpherston,  but  fitted  with  three  beater  rolls 
and  bedplates. 

1894.  Hibrert  (25040). — A  beating  engine  in  which  the 


198 


THE  MANUFACTURE  OF  PAPER 


pulp  is  beaten  between  two  discs  rotating  vertically,  the 
pulp  being  brought  between  the  discs  through  the  hollow 
shaft  of  one  of  the  discs. 

1895.  Brown  (1615). — An  engine  in  which  the  beater  roll 
and  bedplate  both  revolve,  but  in  opposite  directions,  and  at 
different  speeds  in  order  to  draw  out  the  fibres. 

1895.  Schmidt  (24730).^ — A  device  by  means  of  which  the 
pulp  discharged  from  the  beater  roll  is  diverted  into  supple- 
mentary channels  on  either  side  which  come  together  again 
in  front  of  the  beater  roll. 

1900.  Hadfield  (2468). — An  adjustable  baffle  board 
passing  through  the  cover  of  the  beater  roll  which 
prevents  the  j)ulp  being  carried  round  by  the  roll,  more 
or  less. 

1900.  Masson  and  Scott  (5367). — An  improved  form  of 
Taylor  beating  engine  in  which  the  chest  of  the  engine  is 
vertical  instead  of  horizontal. 

1901.  Partington  (24654).  —  A  continuous  elliptical 
trough  provided  with  two  beater  rolls. 

1902.  PiCARD  (19635). — Improvements  in  the  form  of  the 
propellers  used  for  circulating  the  material. 

3  902.  Pope  and  Mullen  (22089).^ — Improvements  in 
propellers  for  dirculatin^]^  the  pulp. 

1903.  Annandale  (26012).  —  A  new  form  of  beating 
engine  somewhat  on  the  principle  of  a  steam  turbine. 

1905.  Bertram  (1727). — A  beater  similar  to  Masson's 
tower  beater,  but  in  which  a  pair  of  reciprocating  wheels 
fitted  with  projecting  knives  are  used  instead  of  a  centrifugal 
pump. 

1907.  Wagg's  Jordan  Engine  (6788). — A  conical  refiner 
fitted  with  specially  arranged  metal  or  stone  knives. 


CHAPTER  X 

THE  DYEING  AND  COLOUEING  OF  PAPER  PULP 

Nearly  all  papers,  even  those  commonly  regarded  as 
white,  are  dyed  with  some  proportion  of  colouring  matter. 
With  the  ordinary  writing  and  printing  papers  the  process 
is  usually  confined  to  the  addition  of  small  quantities  of 
pigments  or  soluble  colours  sufficient  to  tone  the  pulp  and 
correct  the  yellow  tint  which  the  raw  material  possesses 
even  after  bleaching.  In  the  case  of  cover  papers,  tissues, 
and  similar  coloured  papers,  the  process  is  one  of  dyeing  as 
it  is  generally  understood. 

The  colouring  matters  which  have  been  employed  by  the 
paper-maker  are — 

Pigments. 

(A)  Added  to  the  pulp  in  the  form  of  mineral  in  a  finely 
divided  state. 

Yellow. — This  colour  is  obtained  by  the  use  of  ochres^ 
which  are  natural  earth  colours  of  varying  shades, 
from  bright  yellow  to  brown. 

Red. — Ordinary  red  lead. 

Various  oxides  of  iron,  such  as  Indian  red,  Venetian 
red,  red  ochre,  rouge. 

Blue. — Swalts — An  expensive  pigment  prepared  by  grind- 
ing cobalt  glass. 

Ultramarine — A  substance  of  complex  composition 
prepared  by  heating  a  mixture  of  china  clay, 
carbonate   of   goda,   sulphate    of    soda,  sulphur, 


2C0 


THE  MANUFACTUEE  OF  PAPER 


charcoal,  and   sometimes   quartz,  rosin   and  in- 
fusorial earth. 
Prussian    Blue — A  compound   prepared   by  adding 
potassium   ferrocyanide  to  a  solution   of  ferrous 
sulphate. 

Brown. — Natural  earth  colours,  such  as  sienna,  umber, 

Vandyke  brown. 
Black. — Lamp-black,  bone-black,  Frankfort  black. 
(B)  Produced  by  the  reaction  of  soluble  salts  upon  one 
another  when  added  to  the  pulp  in  the  beating  engine. 
Yellow. — Chrome  Yellow — The  paper  pulp  is  first  im- 
pregnated with   acetate  of  lead,  and  potassium  or 
sodium   bichromate   added.      This   precipitates  the 
chromate  of  lead  as  a  yellow  pigment. 
Chrome  Orange — The  addition  of  caustic  alkali  to  the 
bichromate  solution  converts  the  chrome  yellow  into 
an  orange. 

Blue. — Prussian  Blue — The  paper  pulp  impregnated  with 

iron   salts  is  treated  with   potassium  ferrocyanide. 

The  blue  colour  is  at  once  obtained. 
Brown. — Iron  Buff — A  light  yellow-brown  colour  due  to 

the  precipitation  of  ferrous  sulphate  by  means  of  an 

alkali. 

Bronze. — Manganese  chloride  followed  by  caustic  soda. 

Soluble  Colours. 

(A)  Natural  Dyes.  These  colouring  matters  are  now 
seldom  used. 

Yellow  arid  Brown. — The  vegetable  extracts,  such  as 
fustic,  quercitron,  cutch,  turmeric,  have  practically  all 
been  replaced  by  aniline  colours. 

Red. — Madder  (Turkey  red),  Brazilwood,  cochineal  (a  dye 
obtained  from  dried  cochineal  insects).  Safflower, 


THE  DYEING  AND  CODOURING  OF  PAPER  PULP  201 


Black. — Logwood,  used  in  conjunction  with  an  iron  salt. 
Cutch,  used  with  an  iron  salt. 

(B)  Coal  Tar  Dyes.  The  dyeing  and  colouring  of  paper 
pulp  by  means  of  the  artificial  organic  substances  has 
become  a  matter  of  daily  routine,  the  expensive  natural 
dyes  and  the  ordinary  pigments  having  been  almost 
completely  superseded.  The  numerous  colouring  matters 
available  may  be  classified  either  by  reference  to  their 
chemical  constitution  or  simply  on  general  lines,  having 
regard  to  certain  broad  distinctions. 

If  the  latter  classification  is  taken,  then  the  dyes  familiar 
to  the  paper-maker  may  be  divided  into — 

(a)  Acid  dyes,  so  called  because  the  full  effect  of  the 
colouring  matter  is  best  obtained  in  a  bath  showing  an 
acid  reaction. 

{h)  Basic  dyes,  so  called  because  the  colour  is  best 
developed  in  an  alkaline  solution,  without  any  excess 
of  mordant. 

(c)  Substantive  dyes,  which  do  not  require  the  use  of  a 
mordant,  as  the  colour  is  fixed  by  the  fibre  without 
such  reagents. 

Some  of  the  most  frequently  used  colouring  matters  are 
shown  in  the  accompanying  table  on  page  202. 

The  distinction  between  acid  and  basic  dye-stuffs  is  largely 
due  to  certain  characteristics  possessed  by  many  of  them. 
Thus  magenta,  which  is  the  salt  of  the  base  known  as 
Kosaniline,  belonging  to  the  basic  colouring  matters,  a  group 
of  dyes  which  do  not  possess  the  fastness  of  colour  peculiar 
to  acid  dyes,  has  a  limited  application.  But  by  treatment 
with  sulphuric  acid  magenta  is  converted  into  an  acid 
magenta,  and  this  dye  has  wider  application  than  the  basic 
salt.  Similarly  the  basic  dye  called  aniline  blue  is  insoluble 
in  water,  and  therefore  has  only  a  limited  use,  but  by  treat- 
ment with  sulphuric  acid  it  is  converted  into  alkali  blue, 


202 


THE  MANUFACTURE  OF  PAPER 


soluble  blue  and  so  on,  which  dissolve  readily  in  water  and 
are  good  fast  colours.  The  acid  dyes  generally  have  a 
weaker  colouring  power  than  the  basic  dyes,  but  they 
produce  very  even  shades. 

The  difference  in  the  composition  of  the  basic  and  acid 
dyes  is  taken  advantage  of  in  the  dyeing  of  paper  pulp  to 
secure  a  complete  distribution  of  the  colouring  matter  upon 


Colour. 

Acid. 

Basic. 

Substantive. 

Yellow 

Metanil  yellow. 

Auramine. 

Cotton  yellow. 

and 

Paper  yellow. 

Chrysoidine. 

Chrysophenine. 

Orange. 

Orange  II. 

Naphthol  yellow  S. 
Quinoline  yellow. 

Red. 

Fast  red  A. 

Rhodamine. 

Congo  red. 

Cotton  scarlet. 

Paper  scarlet. 

Benzopurpurin. 

Erythrine. 

Safranine. 

Oxamine  red. 

Ponceau. 

Magenta. 

Blue 

Water  blue  1  N. 

Methylene  blue. 

Azo  blue. 

and 

Fast  blue. 

Victoria  blue. 

Violet. 

Acid  violet. 

New  blue. 
Indoine  blue. 
Methyl  violet. 
Crystal  violet. 

Brown 

Naphthylaniine  brown. 

Bismarck  brown. 

Vesuvine. 

Black 

Nigrosine. 
Brillianl  black  B. 

Coal  Black  B. 

Green 

Diamond  green. 
Malachite  green. 

the  pulp,  with  the  result  that  the  intensity  of  colour  is 
increased,  its  fastness  strengthened,  and  the  process  of 
dyeing  generally  rendered  more  economical.  This  is 
effected  by  the  judicious  addition  of  a  suitable  acid  dye  to 
the  pulp  already  coloured  with  the  basic  dye. 

The  direct  colouring  matters  have  but  a  very  limited 
application  for  paper  dyeing  owing  to  their  sensitiveness  to 
acids  and  alkalies. 


THE  DYEING  AND  COLOUEING  OF  PAPER  PULP  203 

In  the  colouring  of  paper  pulp,  attention  is  given  to  many 
important  details,  such  as  : — 

Fading  of  Colour. — Some  loss  of  colour  almost  invariably 
occurs  even  with  dyes  generally  looked  upon  as  fast  to  light. 
The  shade  or  tint  of  the  paper  is  affected  not  only  by  exposure 
to  light,  but  by  contact  of  the  coloured  paper  with  common 
boards  on  which  it  is  often  pasted.  The  alkalinity  of  straw 
boards,  for  example,  is  frequently  one  source  of  serious 
alteration  of  colour,  and  the  acidity  of  badly  made  pastes 
and  adhesives  another. 

In  all  such  cases,  the  dyes  must  be  carefidly  selected  in 
order  to  obtain  a  coloured  paper  which  will  show  a  minimum 
alteration  in  tint  by  exposure  to  light  or  by  contact  with 
chemical  substances.  This  is  particularly  necessary  in 
coloured  wrapping  paper  used  for  soap,  tea,  cotton  yarn, 
and  similar  goods. 

Unevenness  of  Colour. — The  different  affinity  of  the 
various  paper-making  fibres  for  dyes  is  apt  to  produce  an 
uneven  colour  in  the  finished  paper.  This  is  very  notice- 
able in  mixtures  of  chemical  wood  pulp  or  cellulose  and 
mechanical  wood  pulp.  The  lignocellulose  of  the  latter  has 
a  great  affinity  for  basic  dyes,  and  if  the  required  amount 
of  dye  is  added  to  a  beater  containing  the  mixed  pulps  in 
an  insufficiently  diluted  form,  the  mechanical  wood  pulp 
becomes  more  deeply  coloured  than  the  cellulose.  If  the 
former  is  a  finely  ground  pulp,  the  effect  is  not  very  notice- 
able, but  if  it  is  coarse,  containing  a  large  number  of  coarse 
fibres,  then  the  paper  appears  mottled.  The  defect  is  still 
further  aggravated  when  the  paper  is  calendered,  especially 
if  calendered  in  a  damp  condition.  In  that  case  the 
strongly  coloured  fibres  of  mechanical  wood  are  very 
prominent. 

When  dyes  have  been  carelessly  dissolved  and  added 
to  the  beating  engine  without  being  properly  strained, 


204 


THE  MANUFACTURE  OF  PAPER 


unevenness  of  colour  may  often  be  traced  to  the  presence  of 
undissolved  particles  of  dye. 

Irregular'  Colour  of  the  two  Sides.- — Many  papers  exhibit 
a  marked  difference  in  the  colour  of  the  two  sides.  When 
heavy  pigments  are  employed  as  the  colouring  medium,  the 
under  side  of  the  sheet,  that  is,  the  side  of  the  paper  in 
contact  with  the  machine  wire,  is  often  darker  than  the 
top  side.  The  suction  of  the  vacuum  boxes  is  the  main 
cause  of  this  defect,  though  the  amount  of  water  flowing  on 
to  the  wire,  the  shake  "  of  the  wire,  and  the  extent  to 
which  the  paper  is  sized  are  all  contributory  causes.  By 
careful  regulation  of  these  varying  conditions  the  trouble  is 
considerably  minimised. 

The  under  surface  of  the  paper  is  not  invariably  darker 
than  the  top  surface.  With  pigments  of  less  specific  gravity 
the  reverse  is  found  to  be  the  case.  This  is  probably  to  be 
explained  by  the  fact  that  some  of  the  colouring  matter 
from  the  under  side  is  drawn  away  from  the  paper  by  the 
suction  boxes,  and  the  pigment  on  the  top  side  is  not  drawn 
away  to  any  serious  extent,  because  the  layer  of  pulp  below 
it  acts  as  a  filter  and  promotes  a  retention  of  colour  on  the 
top  side. 

It  is  interesting  to  notice  that  this  irregularity  sometimes 
occurs  with  soluble  dyes,  as  for  example  in  the  case  of 
auramine.  The  decomposition  of  this  dye  when  heated  to 
the  temperature  of  boiling  water  is  well  known,  and  the 
contact  of  a  damp  sheet  of  paper  coloured  by  auramine 
with  the  surfaces  of  steam-heated  cylinders  at  a  high 
temperature  brings  about  a  partial  decomposition  of  the 
dye  on  one  side  of  the  paper.  Generally  speaking,  acid 
dyes  are  more  sensitive  to  heat  tban  basic  dyes. 

The  presence  of  china  clay  in  a  coloured  paper  is  also  an 
explanation  of  this  irregular  appearance  of  the  two  sides. 
China  clay  readily  forms   an  insoluble   lake  with  basic 


THE  DYEING  AND  COLOUEING  OF  PAPER  PULP  205 


dyes,  and  when  the  suction  boxes  on  the  machine  are  worked 
with  a  high  vacuum  the  paper  is  apt  to  be  more  deeply- 
coloured  one  side  than  another. 

The  Machine  Backwater. — Economy  in  the  use  of  dyes  to 
avoid  a  loss  of  the  colouring  matter  in  the  "  backwater,"  or 
waste  water  from  the  paper  machine,  is  only  obtained  by 
careful  attention  to  details  of  manufacture  on  the  one  hand 
and  by  a  knowledge  of  the  chemistry  of  dyeing  on  the 
other.  The  loss  is  partly  avoided  by  regulating  the  amount 
of  water  used  on  the  machine,  so  that  very  little  actually 
^oes  to  waste,  and  further  reduced  by  ensuring  as  complete 
a  precipitation  of  the  soluble  dye  as  possible. 

The  acid  dyes  generally  do  not  give  a  colourless  back- 
water, and  all  pulps  require  to  be  heavily  sized  when  acid 
dyes  are  used. 

The  basic  dyes  are  more  readily  precipitated  than  the 
acid  dyes,  particularly  if  a  suitable  mordant  is  used,  even 
with  heavily  coloured  papers.  The  addition  of  an  acid  dye 
to  pulp  first  coloured  with  a  basic  dye  is  frequently  resorted 
to  as  a  means  of  more  complete  precipitation. 

Dyeing  to  Sample. — The  matching  of  colours  has  been 
greatly  simplified  through  the  publication  of  pattern  books 
by  the  firms  who  manufacture  dyes,  in  which  books  full 
details  as  to  the  composition  of  the  paper,  the  proportion  of 
colour  and  the  conditions  for  maximum  effects  are  fully 
set  out.  The  precise  results  obtained  by  treating  paper 
pulp  with  definite  proportions  of  a  certain  dye,  or  a  mixture 
of  several  dyes,  is  determined  by  experimental  trials.  A 
definite  quantity  of  moist  partially  beaten  and  sized  pulp, 
containing  a  known  weight  of  air-dry  fibre,  is  mixed  with  a 
suitable  volume  of  water  at  a  temperature  of  80^  to  90^  F. 
and  the  dye-stuff  added  from  a  burette  in  the  form  of  a 
1  per  cent,  solution.  If  preferred  a  measured  volume  of 
a  1  per  cent,  solution  of  the  dye  can  be  placed  in  a  mortar, 


206 


THE  MANUFACTURE  OF  PAPER 


and  the  moist  pulp,  previously  squeezed  out  by  hand,  added 
gradually  and  well  triturated  with  the  pestle. 

The  dyed  mixture  is  then  suitably  diluted  with  water, 
made  up  into  small  sheets  of  paper  on  a  hand  mould  or  a 
siphon  mould,  and  dried. 

The  effect  of  small  additions  of  colour  to  the  contents  of 
a  beating  engine  is  frequently  examined  in  a  rough  and 
ready  way  by  the  beaterman,  who  pours  a  small  quantity  of 
the  diluted  pulp  on  the  edge  of  the  machine  wire  while  the 
machine  is  running.  This  gives  a  little  rough  sheet  of 
paper  very  quickly. 

The  comparison  of  the  colour  of  a  beaterfull  of  pulp  with 
the  sample  paper  which  it  is  desired  to  match  is  also 
effected  by  reducing  a  portion  of  the  paper  to  the  condition 
of  ]Dulp,  so  that  a  handful  of  the  latter  can  be  compared 
with  a  quantity  of  pulp  from  the  engine.  This  is  not 
always  a  reliable  process,  especially  with  papers  coloured 
by  dyes  which  are  sensitive  to  the  heat  of  the  paper  machine 
drying  cylinders. 

Detection  of  Colours  in  Papers. — The  examination  of 
coloured  papers  for  the  purpose  of  determining  what  dyes 
have  been  employed  is  a  difficult  task.  With  white  papers 
which  have  been  merely  toned  the  j^roportion  of  dye  is 
exceedingly  small,  and  a  large  bulk  of  paper  has  to  be 
treated  with  suitable  solvents  in  order  to  obtain  an  extract 
containing  sufficient  dye  for  investigation. 

With  coloured  papers  dyed  by  means,  of  pigments,  the 
colour  of  the  ash  left  on  ignition  is  some  guide  to  the 
substance  used,  a  red  ash  indicating  iron  oxide,  a  yellow 
ash  chromate  of  lead,  and  so  on. 

With  papers  dyed  by  means  of  coal  tar  colours  the 
nature  of  the  colouring  matter  may  be  determined  by  the 
methods  of  analysis  employed  for  the  examination  of 
textile  fibres. 


THE  "DYEING  AND  COLOURING  OF  PAPER  PULP  207 


The  following  hints  given  by  Kollmann  will  be  found 
useful : — 

Tear  up  small  about  100  grammes  of  paper,  and  boil  it 
in  alcohol,  in  a  flask  or  a  reflux  condenser.  This  must  be 
done  before  the  stripping  with  water,  so  as  to  extract  the 
size  which  would  otherwise  protect  the  dye  from  the  water. 
Of  course  the  alcohol  treatment  is  omitted  with  unsized 
paper.  The  paper  is  now  boiled  with  from  three  to  five 
lots  of  water,  taking  each  time  only  just  enough  to  cover 
the  paper.  This  is  done  in  the  same  flask  after  pouring  off 
any  alcohol  that  may  have  been  used,  and  also  with  the 
reflux  condenser.  The  watery  extract  is  mixed  with  the 
alcohol  extract  (if  any).  Three  cases  may  occur: — (1)  The 
dye  is  entirely  stripped,  or  very  nearly  so.  (2)  The  dye  is 
partly  stripped,  what  remains  on  the  fibres  showing  the 
same  colour  as  at  first  or  not.  (3)  The  dye  is  not  stripped. 
To  make  sure  of  this  the  solution  is  filtered,  as  the  presence 
in  it  of  minute  fragments  of  fibre  deceive  the  eye  as  to  the 
stripping  action.  In  the  first  two  cases  the  mixed  solutions 
are  evaporated  down  to  one  half  on  the  water  bath,  filtered, 
evaporated  further,  and  then  precipitated  by  saturating  it 
with  common  salt.  The  dye  is  thrown  out  at  once,  or  after 
a  time.  It  may  precipitate  slowly  without  any  salt.  The 
precipitated  dye  is  filtered  off  and  dried.  To  see  whether 
it  is  a  single  dye  or  a  mixture,  make  a  not  too  dark  solution 
of  a  little  of  it  in  water,  and  hang  up  a  strip  of  filter  paper 
so  that  it  is  partly  immersed  in  the  solution.  If  the  latter 
contains  more  than  one  dye  they  will  usually  be  absorbed 
to  different  heights,  so  that  the  strip  will  show  bands  of 
different  colours  crossing  it.  If  it  is  found  that  there  is 
only  one  dye,  dissolve  some  of  it  in  as  little  water  as 
possible,  and  mix  it  with  "  tannin-reagent,"  which  is  made 
by  dissolving  equal  weights  of  tannin  and  sodium  acetate 
in  ten  times  the  weight  of  either  of  water.    If  there  is  a 


208 


THE  MANUFACTURE  OF  PAPER 


precipitate  there  is  a  basic  dye,  if  not,  an  acid  dye.  In  the 
former  case  mix  the  strong  sokition  of  the  dye  with  con- 
centrated hydrochloric  acid  and  zinc  dust,  and  boil  tiJl  the 
colour  is  destroyed.  Then  neutralise  exactly  with  caustic 
soda,  filter,  and  put  a  drop  of  the  filtrate  on  to  white  filter 
paper.  If  the  original  colour  soon  reappears  on  drying, 
we  draw  the  following  conclusions  : — 

(a)  The  colour  is  red ;  the  dye  is  an  oxazine,  thiazine, 
azine,  or  acridine  dye,  e.g.,  safranine.  {h)  It  is  orange  or 
yellow ;  the  dye  is  as  in  (a),  e.g.,  phosphine.  (c)  It  is 
green;  the  dye  is  as  in  (a),  e.g.,  azine  green,  (d)  It  is 
blue  ;  the  dye  is  as  in  {<i),  e.g.,  Nile  blue,  new  blue,  fast 
blue,  or  methylene  blue,  {e)  It  is  violet ;  the  dye  is  as  in 
(a),  e.g.,  mauveine.  If  the  original  colour  does  not  reappear 
on  drying,  but  does  so  if  padded  with  a  1  per  cent,  solution 
of  chromic  acid,  we  draw  the  following  conclusions  : — 

(a)  The  colour  is  red ;  the  dye  is  rhodamine  or  f  uchsine, 
or  one  of  their  allies,  (b)  It  is  green  ;  the  dye  is  malachite 
green,  brilliant  green,  or  one  of  their  allies,  (c)  It  is  blue ; 
the  dye  is  night  blue,  Victoria  blue,  or  one  of  their  allies. 
(d)  It  is  violet ;  the  dye  is  methyl  violet,  crystal  violet,  or 
one  of  their  allies. 

If  the  original  colour  does  not  reappear  even  with 
chromic  acid,  it  was  in  most  cases  a  yellow  or  a  brown, 
referable  to  auramine,  chrysoidine,  Bismarck  brown, 
thioflavine,  or  one  of  their  allies. 

If  the  tannin  reagent  produces  no  precipitate,  reduce 
with  hydrochloric  acid  and  zinc,  or  ammonia  and  zinc,  and 
neutralise  and  filter  as  in  the  case  of  a  basic  dye.  The 
solution  when  dropped  on  to  white  filter  paper  may  be 
bleached  (a),  may  have  become  a  brownish  red  (h),  may 
have  been  imperfectly  and  slowly  bleached  (c),  or  may 
have  undergone  no  change  (d). 

(a)  If  the  colour  quickly  returns  the  dye  is  azurine. 


THE  DYEING  AND  COLOUEING  OF  PAPER  PULP  209 


indigo-carmine,  nigrosine,  or  one  of  their  allies.  If  it 
returns  only  on  padding  with  a  1  per  cent,  solution  of 
chromic  acid,  warming,  and  holding  over  ammonia,  some 
of  the  dye  is  dissolved  in  water  mixed  with  concentrated 
hydrochloric  acid,  and  shaken  up  with  ether.  If  the  ether 
takes  up  the  dye,  we  have  aurine,  eosine,  erythrine, 
phloxine,  erythrosine,  or  one  of  their  allies.  If  it  does 
not,  we  have  acid  fachsine,  acid  green,  fast  green,  water 
blue,  patent  blue,  or  one  of  their  allies.  If  the  colour 
never  returns,  heat  some  of  the  dye  on  platinum  foil.  If  it 
deflagrates  with  coloured  fumes,  the  dye  is  aurantia, 
naphthol  yellow  S.,  brilliant  yellow,  or  one  of  their  allies. 
If  it  does  not  deflagrate,  or  very  slightly,  dissolve  a  little  of 
the  dye  in  one  hundred  times  its  weight  of  water,  and  dye  a 
cotton  skein  in  it  at  the  boil  for  about  fifteen  minutes. 
Then  rinse  and  soap  the  skein  vigorously.  If  the  dyeing 
is  fast  with  this  treatment  we  have  a  substantive  cotton 
yellow  or  thiazine  red  ;  if  it  is  not,  we  have  an  ordinary  azo 
dye.  (b)  The  dye  is  an  oxyketone,  such  as  alizarine, 
(c)  The  dye  is  thiazol  yellow,  or  one  of  its  allies,  (d)  The 
dye  is  thioflavine  S.,  quinoline  yellow,  or  one  of  their 
allies. 

If  the  dye  is  not  stripped  by  alcohol  and  water,  it  is 
either  inorganic  or  an  adjective  dye,  such  as  logwood  black, 
cutch,  fustic,  etc. ;  and  we  proceed  according  to  the  colour 
as  follows  : — 

If  it  is  red  or  brown,  the  dyed  fibre  is  dried  and  divided 
into  two  parts.  One  is  boiled  with  bleaching  powder.  If 
it  is  bleached  entirely  or  to  a  large  extent,  the  dye  is  cutch. 
If  the  bleach  has  no  action,  incinerate  some  of  the  dyed 
fibre  in  an  iron  crucible  and  heat  the  ash  on  charcoal  before 
the  blowpipe.  If  a  globule  of  lead  is  formed,  we  have 
saturn  red.  The  second  portion  is  boiled  with  concentrated 
hydrochloric  acid.    If  there  is  no  action,  we  have  Cologne 

p.  .  P 


210 


THE  MANUFACTURE  OF  PAPER 


umber  ;  if  there  is  partial  action,  we  have  real  umber  ;  if 
the  dye  dissolves  completely  to  a  yellow  solution,  we  have 
an  ochre  ;  if  the  solution  is  colourless  instead  of  yellow, 
and  chlorine  is  evolved  during  solution,  we  have  manganese 
brown. 

If  the  colour  is  yellow  or  orange,  boil  with  concentrated 
hydrochloric  acid.  If  we  get  a  green  solution  and  a  white 
residue,  we  infer  chrome  yellow  or  orange.  If  we  get  a 
yellow  solution,  we  boil  it  with  a  drop  or  two  of  nitric  acid 
and  then  add  some  ammonium  sulphocyanide.  A  red 
colour  shows  an  ochre  or  Sienna  earth. 

If  the  colour  is  green,  boil  with  caustic  soda  lye.  If  the 
fibre  turns  brown,  we  have  chrome  green.  If  no  change 
takes  place,  boil  with  concentrated  hydrochloric  acid.  A 
yellow  solution  shows  green  earth ;  a  red  colour  logwood 
plus  fustic. 

If  the  colour  is  blue  or  violet,  boil  with  caustic  soda  lye. 
If  the  fibre  turns  brown,  we  have  Prussian  blue.  If  no 
change  takes  place,  boil  with  concentrated  hydrochloric 
acid.  A  yellow  solution  shows  smalts.  If  the  colour  is 
destroyed,  and  the  smell  of  rotten  eggs  is  developed,  we 
have  ultramarine. 

If  the  colour  is  black,  warm  with  concentrated  hydro- 
chloric acid  containing  a  little  tin  salt.  If  the  black  is 
unchanged,  we  have  a  black  pigment.  If  we  get  a  pink  to 
deep  red  solution  we  have  logwood  black. 

By  means  of  the  tests  above  detailed  at  length  the  group 
to  which  the  dye  belongs  is  discovered,  and  often  the  actual 
dye  itself.  Once  the  group  is  known  it  is  generally  easy, 
by  means  of  the  special  reactions  given  in  many  books, 
cjj.,  in  Schultz  and  Julius's  "  Tabellarische  Ubersicht," 
to  identify  the  particular  dye. 

When  one  has  to  deal  with  a  single  dye  and  simply 
desires  to  determine  its  group,  the  following  table,  due  to 


THE  DYEING  AND  COLOURING  OF  PAPER  PULP  211 


J.  Herzfeld,  will  suffice.  Originally  intended  for  textiles,  it 
will  serve,  with  some  modifications  here  made  in  it,  for  the 
rapid  testing  of  paper. 

1. — Ked  and  Reddish  Brown  Dyes. 

Boil  the  paper  with  a  mixture  of  alcohol  and  sulphate  of 
alumina.  If  no  dye  is  extracted  or  a  fluorescent  solution  is 
formed,  we  have  an  inorganic  pigment,  or  eosine,  phloxine, 
rhodamine,  safranine,  or  one  of  their  allies.  Add  bleaching 
powder  solution,  and  heat.  If  the  paper  is  bleached,  add 
concentrated  hydrochloric  acid.  A  violet  colour  shows 
safranine  or  an  analogue.  If  there  is  no  colour,  but  the 
fluorescence  disappears,  we  have  eosine,  phloxine,  rhoda- 
mine, or  one  of  their  allies.  If  the  paper  is  not  bleached 
test  for  inorganic  colouring  matters.  Cutch  brown  is  partly 
but  not  entirely  bleached. 

If  the  alumina  solution  gives  a  red  or  yellow  solution 
without  fluorescence,  add  to  it  concentrated  sodium  bisul- 
phite. If  bleaching  takes  place,  heat  a  piece  of  the  paper 
with  dilute  spirit.  A  red  extract  shows  sandal  wood,  fuch- 
sine,  etc.  If  there  is  little  or  no  extract,  we  have  acid 
fuchsine  or  one  of  its  allies.  If  the  bisulphite  causes  no 
bleaching,  boil  a  piece  of  the  paper  with  very  dilute  hydro- 
chloric acid.  If  the  colour  is  unchanged,  heat  another 
piece  of  the  paper  with  dilute  acetate  of  lead.  If  no  change 
takes  place,  we  have  an  azo  dye.  If  the  colour  turns  to  a 
dark  brownish  red,  we  have  cochineal  or  the  like.  If  the 
boiling  with  very  dilute  hydrochloric  acid  darkens  the  colour 
we  have  a  substantive  cotton  dye. 

2. — Yellow  and  Orange  Dyes. 

Heat  some  of  the  paper  with  a  not  too  dilute  solution  of 
tin  salt  in  hydrochloric  acid.    If  the  colour  is  unchanged, 

p  2 


212 


THE  MANUFACTURE  OF  PAPER 


with  a  colourless  or  yellow  solution,  boil  some  more  paper 
with  milk  of  lime.  A  change  to  reddish  or  brown  shows 
turmeric  or  a  congener.  Absence  of  change  shows  phosphine, 
quinoline  yellow,  or  a  natural  dye-stuff.  If  the  acid  tin 
solution  turns  the  paper  red,  and  then  quickly  bleaches  it 
to  a  pale  yellow,  we  have  fast  yellow,  orange  IV.,  metanil 
yellow,  brilliant  yellow,  or  the  like.  If  the  tin  turns  the 
paper  greyish,  heat  another  portion  with  ammonium 
sulphide.  A  blackening  shows  a  lead  or  iron  yellow. 
If  there  is  no  change,  we  have  naphthol  yellow,  auramine, 
azoflavine,  orange  11.,  chrysoidine,  or  one  of  their  allies. 

3. — Green  Dyes. 

Heat  a  sample  of  the  paper  in  dilute  spirit.  If  the  spirit 
acquires  no  colour,  warm  for  a  short  time  with  dilute  sul- 
phuric acid.  If  both  paper  and  solution  become  brownish 
red,  we  have  logwood  plus  fustic.  If  this  fails,  boil  with 
concentrated  hydrochloric  acid.  A  yellow  solution  shows 
green  earth.  If  this  fails,  boil  with  concentrated  caustic 
soda.  Browning  shows  chrome  green.  If  the  spirit 
becomes  blue,  it  is  a  case  of  paper  which  has  been  topped 
with  blue  on  a  yellow,  brown,  or  green  ground.  The  solu- 
tion and  the  insoluble  part  are  separately  tested.  The  case 
is  probably  one  of  an  aniline  blue  dyed  over  a  mineral 
pigment.  If  the  spirit  becomes  green,  heat  with  dilute 
hydrochloric  acid.  If  the  fibre  is  completely  or  nearly 
bleached,  and  the  acid  turns  yellow,  the  dye  is  brilliant 
green,  malachite  green,  or  one  of  their  allies. 

4. — Blue  and  Violet  Dyes. 

Heat  some  of  the  paper  with  dilute  spirit.  If  the  alcohol 
remains  colourless,  we  have  Prussian  blue  or  ultramarine. 
If  it  becomes  blue  or  violet,  shake  some  of  the  paper  with 


THE  DYEING  AND  COLOURING  OF  PAPER  PULP  213 


concentrated  sulphuric  acid.  A  dirty  olive  green  shows 
methylene  blue,  and  a  brownish  colour  shows  spirit  blue, 
water  blue,  Victoria  blue,  methyl  violet,  etc.  If  the  spirit 
turns  yellow,  and  the  colour  of  the  paper  changes,  we  have 
wood  blue  or  wood  violet. 


CHAPTEK  XI 


PAPER  MILL  MACHINERY 

In  the  case  of  common  printings  and  writings,  which 
form  the  great  bulk  of  the  paper  made,  the  possibihty  of 
one  mill  competing  against  another,  apart  from  the  im- 
portant factor  of  the  cost  of  freight,  coal,  and  labour,  is 
almost  entirely  determined  by  the  economy  resulting  from 
the  introduction  of  modern  machinery. 

The  equipment  of  an  up-to-date  paper  mill,  therefore, 
comprises  all  the  latest  devices  for  the  efficient  handling  of 
large  quantities  of  raw  material,  the  economical  production 
of  steam,  and  the  minimum  consumption  of  coal,  matters 
which  are  of  course  common  to  most  industrial  operations, 
together  with  the  special  machinery  peculiar  to  the  manu- 
facture of  paper. 

The  amount  of  material  to  be  handled  ma}^  be  seen  from 
the  table  on  pagie  215,  which  gives  the  approximate  quantities 
for  the  weekly  output  of  a  common  news  and  a  good  print- 
ing paper. 

Economy  in  Coal  Consumption. — The  reduction  to  a 
minimum  of  the  amount  of  coal  required  for  a  ton  of  paper 
has  been  brought  about  by  the  use  of  appliances  for  the 
better  and  more  regular  combustion  of  the  coal,  such  as 
mechanical  stokers,  forced  and  induced  draught,  the  intro- 
duction of  methods  for  utilising  waste  heat  in  flue  gases 
by  economisers,  and  the  waste  heat  in  exhaust  steam  and 
condensed  water  by  feed-water  heaters,  the  adoption  of 
machines  for  securing  the  whole  energy  of  the  live  steam 


PAPER  MILL  MACHINEEY 


215 


by  means  of  superheaters,  adequate  insulation  of  steam 
mains  and  pipes,  high  pressure  boilers,  and  engines  of  most 
recent  design. 

The  firing  of  steam  boilers  is  now  conducted  on  scientific 
principles,  the  coal  being  submitted  regularly  to  proper 
analysis  for  calorific  value,  the  evaporative  power  of  the 
boilers  being  determined  at  intervals  by  adequate  trials, 
the  condition  of  the  waste  flue  gases  being  automatically 

Table  showing  the  Materials  required  for  News 
AND  Printings. 


Weekly  output  of  paper,  say 
Mechanical  wood  pulp,  moist 

50  per  cent,  dry  . 
Chemical  wood  pulp,  dry 
Esparto  . 
Soda  ash  . 
Coal  . 
Lime 

China  clay 
Bleach 

Alum,  rosin,  and  chemicals 
Water,  per  ton  paper 


Common  News. 


600  tons 

800  „ 
200  „ 

Nil. 

Nil. 
600  tons 

Nil. 
60  tons 

Nil. 
20  tons 
,000  gallons 


Good  Printings. 


250  tons 

Nil. 

150  tons 
200  „ 

16  „ 
800  ,, 

45  ,, 

25  „ 

30  ,, 

20  „ 
40,000  gallons 


recorded  in  order  to  obtain  regular  and  maximum  com- 
bustion. 

The  Sarco  Combustion  llecorder. — This  instrument  is  a 
device  which  automatically  records  the  percentage  of  car- 
bonic acid  gas  in  the  waste  gases  from  boiler  furnaces.  The 
flue  gases  are  analysed  at  frequent  and  regular  intervals, 
and  the  results  of  the  analysis  can  be  seen  on  a  chart 
immediately,  so  that  it  is  possible  to  determine  the  eft'ect  of 
an  alteration  in  the  firing  of  the  boilers  within  two  minutes 
of  its  taking  place.  The  apparatus  is  rather  complicated, 
but  the  principle  upon  which  it  is  based  is  simple. 


216 


THE  MANUFACTURE  OF  PAPER 


Measured  quantities  of  the  flue  gases  are  drawn  into 
graduated  glass  tubes  and  brought  into  contact  with  strong 
caustic  soda  solution,  which  absorbs  all  the  carbonic  acid 
gas.   The  remaining  gases  not  absorbed  by  the  caustic  soda 

are  automatically  mea- 
sured and  the  percentage 
of  carbonic  acid  gas  re- 
gistered on  the  chart. 

The  use  of  suitable 
boiler  feed-water  is  also 
an  important  factor  in 
modern  steam  -  raising 
plant.  The  hot  condensed 
water  from  the  paper 
machine  drying  cylinders, 
and  exhaust  steam  from 
the  engines  and  steam- 
pipes,  is  returned  to  the 
stoke-hole  to  be  utilised 
in  heating  up  the  cold 
water  which  has  been 
previously  softened  by 
chemical  treatment. 

Water  Softening. — The 
water  softeners  available 
on  the  market  are  numer- 
ous, and  as  each  possesses 
special  advantages  of  its 
own,  it  would  be  almost  invidious  to  select  any  one  for 
particular  notice. 

They  are  based  upon  the  principle  of  mixing  chemicals 
with  the  water  to  be  treated,  so  as  to  precipitate  the  matters 
in  solution  and  give  a  boiler  feed-water  free  from  carbonates 
and  sulphates  of  lime  and  magnesia.    The  chemicals  are 


Fig.  55. — Conventional  Diagram  of  a 
Water  Softening  Plant. 

A.  Water  supply. 

B.  Regulating  tank. 

C.  Lime  mixer. 

D.  Soda  tank. 

E.  Settling  tank  and  filter. 

F.  Outlet  for  softened  water. 


PAPER  MILL  MACHINERY 


217 


added  in  the  form  of  solutions  of  carefully  regulated 
strength  to  the  water,  which  flow  in  a  continuous  stream 
into  a  tank.  The  flow  of  the  water  and  chemical  reagent  is 
adjusted  by  previous  analysis. 

The  various  machines  differ  in  details  of  construction,  and 
in  the  methods  by  which  the  mixing  of  the  water  and  re- 
agents is  effected.  The  object  to  be  achieved  is  the  complete 
precipitation  of  the  dissolved  salts  and  the  production  of  a 
clear  water,  free  from  sediment,  in  an  apparatus  that  will 
treat  a  maximum  quantity  of  water  at  a  cheap  rate  per 
1,000  gallons. 

The  process  needs  proper  attention.  The  addition  of 
reagents  in  wrong  proportions  will  do  more  harm  than 
good,  and  possibly  result  in  hardening  the  water  instead  of 
softening  it.    The  following  may  be  quoted  as  an  example  : — 


Composition  of  Water. 

Before 
Treatment. 

After 
Treatment. 

Change. 

Calcium  carbonate  . 
Calcium  oxide  (lime) 
Calcium  silicate 
Calcium  sulphate 
Magnesia  .... 
Ferric  oxide,  etc. 

13-863 
00 
2  062 
1-625 
0-0 
0-447 

38-920 
14-300 
3-591 
2-121 
0-266 
0-987 

25-057  gain 
14-300 

1-529 

0-496  ,, 

0-266  ,, 

0-540 

Scale  forming  minerals . 

17-997 

60-185 

42-188  gain 

Calcium  chloride 
Magnesium  chloride 
Sodium  chloride 

1-331 
0-672 
0-478 

2-114 

0-0 

0-476 

0-783  gain 
0-672  loss 
0-003  „ 

Soluble  salts  . 

2-482 

2-590 

0-108  gain 

Total  mineral  matter 

20-479 

62-776 

42-297  gain 

Carbonic  acid  gas 
Oxygen  gas 

9-71 
0-66 

0-0 
0-66 

9-71  loss 
0-0 

Treatment  required:  1-8  lbs.  of  lime,  0-2  lbs.  soda  ash  per  1,000 
gallons.  Apparently  5-5  lbs.  of  lime  were  being  used  and  no 
soda  (Stromeyer). 


218 


THE  MANUFACTURE  OF  PAPER 


Superheated  Steam.  —  The  effective  application  of  the 
energy  of  the  high  pressure  steam  is  probably  one  of  the 
most  important  problems  in  paper  mill  economy.  The  use 
of  superheated  steam  is  being  extended  in  every  direction, 
and,  in  addition  to  the  advantages  obtained  in  the  steam 
engine  itself,  its  wider  possibilities  for  the  boiling  of  esparto, 
wood,  and  fibres  generally  have  been  noted.  The  following 
case  may  be  quoted  as  the  result  of  a  trial  at  a  paper  mill, 
showing  for  stated  conditions  the  advantages  of  superheated 
steam  : — 


Superheated 
Steam. 

'  Ordinary 
Steam. 

Duration  of  test  hours  . 

26 

34 

Coal  consumed  (lbs.) — 

Per  hour  .... 

61()-5 

661-5 

Per  1  h.-p.  hour  . 

1-83 

2-08 

Water  evaporated  (lbs.) — 

Per  hour  .... 

4,832 

5,679 

Per  1  h.-p.  hour. 

11-55 

17-8 

From  and  at  212^^  F.  . 

8-7 

8-94 

Steam,  temperature  F.  . 

464 

334 

Pressure  .... 

90-3 

90-8 

Steam  engine — 

1  h.-p.  total 

331-5 

323-2 

Temperature  F.  . 

381-8 

333-8 

Coal  used  "per  1  h.-p.— 

Per  hour  at  boiler 

1-83 

2-08 

This  appears  to  show  a  saving  of  12  per  cent. 

Gas  Producers. — The  substitution  of  gas  for  steam  in  the 
paper  mill  has  not  yet  proved  a  success.  The  fact  that  heat 
is  required  for  the  drying  cylinders  of  a  paper  machine,  and 
that  the  heat  is  most  cheaply  and  readily  obtained  in  the 
form  of  exhaust  steam  from  the  engines  driving  the  paper 
machine,  militates  considerably  against  economies  which 
might  otherwise  be  possible.    The  difficulties  of  heating 


PAPER  MILL  MACHINERY 


219 


such  cylinders,  or  rather  of  properly  controlling  and  regu- 
lating the  temperature  by  any  other  means  than  steam,  may 
easily  be  surmised. 

Gas  engines  of  over  200  h.-p.  seem  to  give  considerable 
trouble  at  present,  but  no  doubt  in  course  of  time  the 
required  improvements  will  be  effected. 

It  is  generally  supposed  that  gas  producers  can  only  be 
economical  when  utilised  for  the  production  of  gas  on  a  large 
scale,  and  for  distribution  to  engines  of  smaller  capacity 
than  the  main  steam  engine  required  in  a  paper  mill.  The 
peculiar  conditions  of  the  manufacture  of  paper  do  not 
appear  to  be  favourable  to  the  adoption  of  the  gas  producer 
system  in  its  present  form. 

Motive  Power. — ^The  paper-maker  has  taken  advantage  of 
every  modern  improvement  in  steam  engines  for  the  purpose 
of  reducing  the  cost  of  motive  power.  Amongst  other 
alterations  in  this  direction  the  use  of  a  high  speed  enclosed 
engine  and  the  employment  of  the  modern  steam  turbine 
may  be  noted. 

In  the  enclosed  engine  the  working  parts  are  boxed  in  by 
a  casing  fitted  with  oil-tight  doors.  The  cranks  and  con- 
necting rods  splash  into  the  oil,  which  is  thus  thrown  about 
in  all  directions,  so  as  to  ensure  sufficient  lubrication. 
Another  feature  of  this  engine  is  the  variable  speed,  and  it 
is  possible  to  run  the  paper  machine  at  speeds  varying  from 
100  to  500  ft.  per  minute  without  the  use  of  change 
wheels. 

Electrical  Driving. — The  application  of  electricity  for 
motive  power  has  made  steady  advances  in  the  paper  mill. 
At  first  it  was  limited  to  the  driving  of  machinery  in 
which  variations  of  speed  or  load  were  not  required  to  any 
large  extent,  but  of  recent  years  beating  engines,  calenders, 
and  paper  machines  have  all  been  fitted  with  electrical 
drives. 


Fig.  56.— An  "enclosed"  Steam  Engine. 


PAPER  MILL  MACHINERY 


221 


The  following  details  relate  to  the  installation  at  the 
Linwood  Paper  Mills  : — 

The  installation  consists  of  250-K.W.  steam  dynamos. 
The  engines  are  Willan's  high  speed  triple  expansion, 
working  with  a  boiler  pressure  of  250  lbs.  per  square  inch 
at  the  stop  valve,  the  steam  being  superheated  to  give  a 
temperature  of  500°  Fahr.  at  the  engine.  By  means  of  jet 
condensers  a  vacuum  of  25  to  25J  inches  is  obtained  on  the 
engines.  The  two  boilers  are  of  the  Babcock  type,  and 
have  3,580  square  feet  of  heating  surface  each.  The  furnaces 
have  chain  grate  stokers,  and  the  boilers  are  arranged  with 
their  own  superheaters.  The  motor  equipment  consists  of 
eight  80,  two  50,  and  ten  25  B.H.P.  motors. 

Six  of  the  80  B.H.P.  drive  the  beating  engines,  and  it  has 
been  found  that  the  motors  readily  respond  to  an  overload 
of  50  per  cent,  without  beating  or  other  trouble.  To  remedy 
the  excessive  and  sudden  variation  a  belt  drive  was  adopted. 
An  80  motor  drives  the  pulp  refining  engine.  The  two 
paper-making  machines  have  each  two  motors,  one  a  25  and 
a  50  and  the  other  two  25  B.H.P.  motors.  The  sjDeed  can 
be  regulated  with  exactitude.  The  auxiliary  plant  of  the 
paper-making  machine,  pumps,  agitators,  etc.,  is  worked 
from  lines  of  shafting  driven  by  motors. 

Calender  motors  are  of  the  variable  speed  type,  being 
designed  to  run  from  100  revolutions  per  minute  to  600 
revolutions  per  minute.  Variations  from  300  to  600 
revolutions  per  minute  can  be  regulated  by  the  shunts,  the 
loss  being  negligible.  Several  of  the  motors  are  geared  up 
to  the  various  machines,  as  is  the  case  with  the  calender. 

As  regards  cost,  the  capital  outlay  on  the  500-K.W. 
generating  plant,  including  engines,  dynamos,  boilers, 
condensers,  steam  pipes,  filters,  etc.,  and  all  engine  room 
accessories,  was  ^9,500. 

In  addition  to  the  above,  the  plant  also  contains  a  Parson's 


222 


THE  MANTJFACTUBE  OF  PAPER 


PAPEE  MILL  MACHINEEY 


223 


steam  turbine  of  1,000  K.W.,  driving  two  continuous  current 
dynamos. 

The  Eihel  Patent. — One  of  the  most  important  improve- 
ments in  connection  with  the  manufacture  of  newspaper  is  the 
Eibel  process,  designed  to  increase  the  speed  of  the  machine 
and  to  reduce  the  amount  of  suction  at  the  vacuum  box.  In 
the  ordinary  machine  the  wire  has  usually  been  arranged 
to  move  in  a  horizontal  plane.  In  some  machines  means 
have  been  provided  for  adjusting  the  breast-roll  end  of  the 
wire  to  different  elevations  to  provide  for  dealing  with 
different  grades  of  stock,  but  the  wire  has  never  hitherto 
been  so  inclined  as  to  cause  the  paper  stock  to  travel  at  a 


Fig.  58. — Diagram  of  the  "Eibel"  Process. 


speed,  under  the  action  of  gravity,  to  equal  or  approxi- 
mate the  speed  of  the  wire.  In  all  previous  methods  of 
working,  the  wire  has  for  a  considerable  portion  of  its 
length,  starting  from  the  breast-roll,  drawn  the  stock  along 
in  consequence  of  the  wire  moving  much  faster  than  the 
stock,  and  the  stock  has  waved,  or  rippled,  badly  near  the 
breast-roll  end  of  the  wire.  This  has  gradually  diminished 
until  an  equilibrium  has  been  established  and  an  even  surface 
obtained,  but  not  until  the  waving  or  rippling  has  ceased  at 
some  considerable  distance  from  the  breast-roll  have  the 
fibres  become  laid  uniformly,  and  the  machines  have  there- 
fore necessarily  been  run  slowly  to  give  ample  time  for  the 
water  to  escape  and  for  the  fibres  to  lie  down  so  as  to  make 
them  a  uniform  sheet.    In  many  cases  the  breast-roll  has 


224 


THE  MANUFACTURE  OF  PAPER 


been  raised  14  or  15  inches,  and  the  stock  rushes,  as  it  were, 
downhill. 

As,  during  the  formation  of  the  paper,  the  stock  and  the 
wire  practically  do  not  move  relatively  to  each  other,  there 
is  no  drag  of  the  stock  upon  the  wire ;  consequently  there  is 
a  more  rapid  and  uniform  drainage  of  the  water  from  the 
stock,  the  full  influence  of  the  "  shake"  is  made  effective  to 
secure  uniformity  in  the  distribution  and  interlocking  of  the 
fibres,  and  the  regularity  of  the  formation  of  the  paper  is 
not  disturbed  by  waves  or  currents,  which  would  otherwise 
be  caused  by  pull  of  the  wire  upon  the  stock. 

This  ingenious  device  is  now  working  successfully  in 
many  paper  mills. 

Machinery. — In  setting  out  the  plant  necessary  for  a 
paper  mill  which  is  designed  to  produce  a  given  quantity 
of  finished  paper,  the  manufacturer  takes  into  consideration 
the  class  of  paper  to  be  made  and  the  raw  material  to  be 
employed.  The  following  schedule  has  been  prepared  on 
such  a  basis  : — 

Plant  and  Machinery  for  High-class  Printings. 
Fape7\ 

High-class  printings  made  of  wood  pulp  and  esparto, 
used  alone  or  blended  in  varying  proportions  as 
required.     Quantity,  250  tons  weekly. 
liaiv  Material. 

Esparto ;  chemical  wood  pulp. 

Quantity:  esparto,  about  200  tons;  wood  pulp,  150 
to  160. 

China  clay  and  usual  chemicals. 
In  the  estimation  of  materials  required  for  the  production 
of  about  250  tons  of  paper,  it  is  assumed  that  the  200  tons 
of  esparto  fibre  will  yield  90  tons  bleached  esparto  fibre,  and 


PAPER  MILL  MACHENEEY 


225 


that  the  mechanical  losses  which  take  place  during  manu- 
facture are  counterbalanced  by  the  weight  of  china  clay 
added  to  the  pulp.  These  conditions  naturally  vary  in 
different  mills,  but  such  variations  do  not  affect  the  schedule 
of  machinery. 
Unloading  Sheds. 

2  steam  or  electric  cranes  for  handling  fibre,  clay,  alum, 
bleach,  rosin,  coal,  and  finished  paper. 

1  3-ton  weighbridge. 

1  5-cwt.  platform  scales. 
Steain  Plant. 

6  8-ft.  by  30-ft.  Lancashire  boilers. 

Fuel  economiser. 

Feed-w^ater  pump  and  tank. 

Water  softening  apparatus. 

1  500-h.-p.  main  steam  engine,  for  fibre  departments 
and  beater  floor. 

Chemical  Department. 

Hoist  for  clay,  alum,  bleach,  lime,  &c. 

4  causticising  pans,  9  ft.  diameter,  9  ft.  deep. 

2  storage  tanks. 

2  chalk  sludge  filter  presses. 

2  clay-mixing  vats,  6  ft.  diameter,  6  ft.  deep. 
1  starch  mixer,  6  ft.  diameter,  6  ft.  deep. 

1  size  boiler,  8  ft.  diameter,  8  ft.  deep. 

3  size  storage  tanks,  1,000  gallons  each. 
3  bleach-mixing  vats. 

3  bleach  liquor  settling  tanks. 

2  clear  bleach  liquor  storage  tanks. 
1  alum  dissolving  tank. 

Recovery  Department : — 
Soda. 

1  multiple  effect  evaporating  plant. 
1  rotary  furnace. 
P-  Q 


'226 


THE  MANUFACTTJRE  OF  PAPEE 


4  lixiviating  tanks,  2,000  gallons  each. 

2  storage  tanks  for  clear  liquor  froro  lixiviating  tanks, 

20,000  gallons  capacity. 

Fibre. 

2  tanks  for  receiving  machine  backwater. 

2  Fullner's  stuff  catchers,  or  some  other  system  of 

treating  backwater. 
2  filter  presses. 
Espa7'to  Department. 

1  esparto  duster. 

Travelling  conveyer  for  cleaned  esparto. 

6  Sinclair  vomiting  boilers,  each  of  3  tons  capacity. 

2  measuring  tanks  for  caustic  liquor. 
4  washing  engines,  15  cwt.  capacity. 
6  Tower  bleaching  engines. 

1  press-pate. 

10  galvanised  iron  trucks. 
Wood  Pulp  Department. 

4  pulp  disintegrators  and  pumps. 

4  Tower  bleaching  engines. 

4  washing  tanks  or  drainers. 

6  galvanised  iron  trucks. 
Beater  Floor. 

8  1,200-lbs.  beating  engines. 

2  Marshall  refiners. 

6  galvanised  iron  trucks. 
Paper  Machine  Room. 

2  paper  machines,  106  in.  wide,  with  stuff  chests, 
strainers,  and  engines  complete. 

1  paper  machine,  120  in.  wide,  with   stuff  chests, 
strainers,  and  engines  complete. 

Patent  dampers  for  each  machine. 
Calendering  Room. 

2  110-in.  supercalenders. 


PAPER  MILL  MACHINERY 


227 


2  100-in.  supercalenders. 
2  6-reel  cutters. 

1  200-b.-p.  main  steam  engine. 
FinisJiing  Room. 

Sorting  tables. 

Packing  press. 

Weighing  machine. 
Repairs  Department. 

Usual  repair  outfit,  such  as  lathes,  planing  machine, 
drilling  tools,  etc. 

Blacksmith's  shop  outfit. 

Carpenter's  shop  outfit. 

Calender  roll  grinder. 
Water  Supply. 

Main  storage  tank,  50,000  gallons  capacity. 

Water  pumps. 

Piping  and  connections  to  various  departments. 
Bell's  patent  filters  (if  necessary). 


CHAPTEK  XII 


THE  DETERIORATION  OF  PAPER 

Eecent  complaints  about  the  quality  of  paper  and  the 
rapid  decay  of  manuscripts  and  papers  have  resulted  in 
arousing  some  interest  in  the  subject  of  the  durability  of 
paper  used  for  books  and  legal  documents,  and  in  the 
equally  imj^ortant  question  of  the  ink  employed.  The 
Society  of  Arts  and  the  Library  Association  in  England 
and  the  Imperial  Paper  Testing  Institute  in  Germany  have 
already  appointed  special  committees  of  inquiry,  and  from 
this  it  is  evident  that  the  subject  is  one  of  urgent  importance. 

It  is  sometimes  argued  that  the  lack  of  durability  is 
due  to  the  want  of  care  on  the  part  of  manufacturers  in 
jDreserving  the  knowledge  of  paper-making  as  handed  down 
by  the  early  pioneers,  but  such  an  argument  is  superficial 
and  utterly  erroneous.  The  quality  of  paper,  in  common 
with  the  quality  of  many  other  articles  of  commerce,  has 
suffered  because  the  demand  for  a  really  good  high-class 
material  is  so  small.  The  general  public  has  become 
accustomed  to  ask  for  something  cheap,  and  since  the 
reduction  in  price  is  only  rendered  possible  by  the  use  of 
cheap  raw  material  and  less  expensive  methods  of  manu- 
facture, the  paper  of  the  present  day,  with  cettain  exceptions, 
is  inferior  to  that  of  fifty  years  ago. 

The  causes  which  favour  the  deterioration  of  paper  are 
best  understood  by  an  inquiry  into  the  nature  of  the  fibres 
and  other  materials  used  and  the  methods  of  manufacture 
employed. 


THE  DETERIOEATION  OF  PAPER 


229 


The  Fibres  Used. — Cotton  and  linen  rags  stand  pre- 
eminent amongst  vegetable  fibres  as  being  the  most  suitable 
for  the  production  of  high-class  paper  capable  of  with- 
standing the  ravages  of  time.  This  arises  from  the  fact 
that  cotton  and  linen  require  the  least  amount  of  chemical 
treatment  to  convert  them  into  paper  pulp,  since  they  are 
almost  pure  cellulose,  cotton  containing  98*7  per  cent,  of  air- 
dry  cellulose,  and  flax  90*6  per  cent.  The  processes  through 
which  the  raw  cotton  and  flax  are  passed  for  the  manu- 
facture of  textile  goods  are  of  the  simplest  character,  and 
the  rags  themselves  can  be  converted  into  paj^er  without 
chemical  treatment  if  necessary.  As  a  matter  of  fact 
certain  papers,  such  as  the  0.  W.  S.  and  other  drawing 
papers,  are  manufactured  from  rags  without  the  aid  of 
caustic  soda,  bleach,  or  chemicals.  The  rags  are  carefully 
selected,  boiled  for  a  long  time  in  plain  water,  broken  up 
and  beaten  into  pulp,  and  made  up  into  sheets  by  purely 
mechanical  methods. 

The  liability  of  papers  to  decay,  in  respect  of  the  fibrous 
composition,  is  almost  in  direct  proportion  to  the  severity 
of  the  chemical  treatment  necessary  to  convert  the  raw 
material  into  cellulose,  and  the  extent  of  the  deviation  of 
the  fibre  from  pure  cellulose  is  a  measure  of  the  degradation 
which  is  to  be  expected.  The  behaviour  of  the  fibres 
towards  caustic  soda  or  any  similar  hydrolytic  agent  serves 
to  distinguish  the  fibres  of  maximum  durability  from  those 
of  lesser  resistance.  It  may  be  noted  that  in  the  former 
the  raw  materials,  viz.,  cotton,  linen,  hemp,  ramie,  etc., 
contain  a  high  percentage  of  pure  cellulose,  while  in  the 
latter  the  percentage  of  cellulose  is  very  much  lower, 
such  fibres  as  esparto,  straw,  wood,  bamboo,  etc.,  giving 
only  40 — 50  per  cent,  of  cellulose.  The  two  extremes  are 
represented  by  i^ure  cotton  rag  and  mechanical  wood 
pulp.     Other  things  being  equal,  the  decay  which  may 


230 


THE  MANUFACTURE  OF  PAPER 


take  place  in  papers  containing  the  fibre  only,  without  the 
admixture  of  size  or  chemicals,  may  be  considered  as  one 
of  oxidation,  which  takes  place  slowly  in  cotton,  and  much 
more  rapidly  with  mechanical  wood  pulp.  Experimental 
evidence  of  this  oxidation  is  afforded  when  thin  sheets 
of  paper  made  from  these  materials  are  exposed  to  a 
temperature  of  100°  to  110°  C.  in  an  air  oven.  The  cotton 
paper  is  but  little  affected,  while  the  mechanical  wood  pulp 
paper  soon  falls  to  pieces. 

The  order  of  durability  of  various  papers  in  relation  to 
the  fibrous  constituents  may  be  expressed  thus :  (1)  rag 
cellulose ;  (2)  chemical  wood  cellulose ;  (3)  esparto,  straw, 
and  bamboo  celluloses;  (4)  mechanical  wood  pulp.  The 
rate  and  extent  of  oxidation  is  approximately  shown  by  the 
effect  of  heat  as  described.  The  differences  between  the 
celluloses  are  also  shown  by  heating  strips  of  various  papers 
in  a  weak  solution  of  aniline  sulphate,  which  has  no  effect 
on  wood  or  rag  cellulose,  dyes  esparto  and  straw  a  pinkish 
colour,  and  imparts  a  strong  yellow  colour  to  mechanical 
wood  pulp  and  jute. 

Physical  Qualities. — The  permanence  of  a  paper  depends 
not  only  upon  the  purity  of  the  fibrous  constituents  and  the 
freedom  from  ^chemicals  likely  to  bring  about  deterioration, 
but  also  upon  the  general  physical  properties  of  the  paper 
itself.  Other  things  being  equal,  the  more  resistant  a  paper 
is  to  rough  usage  the  longer  will  it  last.  The  reason  why 
rag  papers  are  so  permanent  is  that  not  only  is  the  chemical 
condition  of  the  cellulose  of  the  highest  order,  but  the 
physical  structure  of  the  fibre  is  such  that  the  strength  of 
the  finished  paper  is  also  a  maximum. 

The  methods  of  manufacture  may  be  modified  to  almost 
any  extent,  giving  on  the  one  hand  a  paper  of  extraordinary 
toughness,  or  on  the  other  hand  a  paper  which  falls  to 
pieces  after  a  very  short  time.    Thus  a  strong  bank-note 


THE  DETEEIOEATION  OF  PAPER 


231 


paper  may  be  crumpled  up  between  the  fingers  three  or  four 
hundred  times  without  tearing,  while  an  imitation  art  paper 
is  broken  up  when  crumpled  three  or  four  times. 

A  thorough  study  of  the  physical  qualities  of  a  paper  is 
therefore  necessary  to  an  appreciation  of  the  conditions  for 
durability.  The  physical  structure  of  the  fibre,  the  modifi- 
cations produced  in  it  by  beating,  the  effect  of  drying,  sizing, 
and  glazing  upon  the  strength  and  elasticity  of  the  finished 
paper,  are  some  of  the  factors  which  need  to  be  considered. 

Strength. — The  strength  of  a  paper  as  measured  hy  the 
tensile  strain  required  to  fracture  a  strip  of  given  width,  and 
the  percentage  of  elongation  which  the  paper  undergoes  when 
submitted  to  tension,  are  properties  of  the  utmost  import- 
ance. The  elasticity,  that  is,  the  amount  of  stretch  under 
tension,  has  not  received  the  attention  from  paper-makers 
that  it  deserves.  If  two  papers  of  equal  tensile  strength 
differ  in  elasticity,  it  may  be  taken  for  granted  that  the 
paper  showing  a  greater  percentage  of  elongation  under 
tension  is  the  better  of  the  two. 

The  strength  of  a  paper,  as  already  indicated,  is  greatly 
influenced  by  the  conditions  of  manufacture.  This  has 
been  explained  in  the  chapter  devoted  to  the  subject 
of  beating,  and  other  examples  are  briefly  given  in  the 
following  paragraphs. 

Bulk. — The  manufacture  during  recent  years  of  light 
bulky  papers  for  book  production  has  accentuated  the 
problem  in  a  marked  degree,  and  the  factor  of  bulk  as  one 
of  the  causes  of  deterioration  is  therefore  a  comparatively 
new  one.  It  is  interesting  to  notice  that  the  rapid  destruc- 
tion of  such  books  by  frequent  use  is  in  no  way  related  to 
the  chemical  purity  of  the  cellulose  of  which  it  is  composed, 
or  to  the  influence  of  any  chemical  substance  associated 
with  the  fibre.  It  is  purely  a  mechanical  question,  to  be 
explained  by  reference  to  the  process  of  manufacture. 


232 


THE  MANUFACTUEE  OF  PAPER 


This  paper  is  made  from  esparto  entirely,  or  from  a 
mixture  of  esparto  and  wood  pulp.  The  pulp  is  beaten 
quickly,  and  for  as  short  a  time  as  possible,  little  or  no 
china  clay  being  added,  and  only  a  very  small  percentage 
of  rosin  size.  The  wet  sheet  of  paper  is  submitted  to  very 
light  pressure  at  the  press  rolls,  and  the  bulky  nature  is 
preserved  by  omitting  the  ordinary  methods  of  calendering. 

The  paper  thus  produced  consists  of  fibres  which  are  but 
little  felted  together.  The  physical  condition  and  structure 
of  the  paper  are  readily  noticeable  to  the  eye,  and  when  these 
peculiarities  are  reduced  to  numerical  terms  the  effect  of 
the  conditions  of  manufacture  is  strikingly  displayed. 

The  effect  of  this  special  treatment  is  best  seen  by  con- 
trasting the  bulky  esparto  featherweight  paper  with  the 
normal  magazine  paper  made  from  esparto.  In  the  latter 
case  a  smoother,  heavier,  stronger  sheet  of  paper  is  made 
from  identically  the  same  raw  material.  But  the  pulp  is 
beaten  for  a  longer  period,  while  mineral  matter  and  size 
are  added  in  suitable  proportions.  The  press  rolls  and 
calenders  are  used  to  the  fullest  extent. 

The  difference  between  these  two  papers,  both  consisting, 
as  they  do,  of  pure  esparto  with  a  small  proportion  of  ash 
may  be  emphasised  by  comparing  the  analysis  by  iveight  with 
analysis  hy  volume.  The  two  papers  in  question  when  analysed 
by  weight  proved  to  have  the  following  composition  : — 


Parts  by  Weight. 

Featherweight. 

Ordinary. 

Esparto  fibre 

96-0 

95-4 

Ash,  etc. 

4-0 

4-6 

100-0 

100-0 

THE  DETEEIO  RATION  OF  PAPER 


233 


But  if  the  papers  are  compared  in  terms  of  the  composition 
by  volume,  it  will  be  found  that  the  featherweight  contains 
a  large  amount  of  air  space. 


Composition  by  Volume. 

Featherweight. 

Ordinary. 

Esparto  fibre 

28-0 

65-5 

Ash,  etc. 

0-7 

1-8 

Air  space 

71-3 

32-7 

100-0 

100-0 

In  other  words,  the  conditions  of  manufacture  for  the 
bulky  paper  are  such  that  the  fibres  are  as  far  apart  from 
one  another  as  possible,  and  the  cohesion  of  fibre  to  fibre 
is  reduced  to  a  minimum. 

While  paper  of  this  description  is  agreeable  to  the  printer, 
and  probably  to  the  general  reading  public,  yet  its  strength 
and  physical  qualities,  from  the  point  of  view  of  resistance 
to  wear  and  tear,  are  of  the  lowest  order.  It  is  very  difficult 
to  rebind  books  made  from  it,  which  is  not  altogether  to  be 
wondered  at,  seeing  that  the  bookbinder's  stitches  can 
hardly  be  expected  to  hold  together  sheets  containing  60  to  70 
per  cent,  of  air  space. 

This  concrete  case  emphasises  the  necessity  for  including 
in  a  schedule  of  standards  of  quality  a  classification  of 
papers  according  to  strength  and  bulk. 

Surface. — The  introduction  of  new  methods  of  printing 
has  brought  about  some  changes  in  the  process  of  glazing 
and  finishing  paper  which  are  not  altogether  favourable  to 
the  manufacture  of  a  sheet  having  maximum  qualities  of 
strength  and  elasticity,  two  conditions  which  are  essential 


234 


THE  MANUFACTUEE  OF  PAPEE 


to  permanence.  In  other  words,  the  very  high  finish  and 
surface  imparted  to  paper  by  plate-glazing,  supercalendering, 
water  finish,  and  other  devices  of  a  similar  character  is 
carried  to  excess. 

All  papers  are  improved  in  strength  by  glazing  up  to  a 
certain  point,  but  over-glazing  crushes  the  paper,  renders 
it  brittle  and  liable  to  crack.  Unfortunately,  the  maximum 
strength  of  a  paper  is  generally  reached  before  the  maximum 
of  finish,  with  the  result  that  the  former  is  frequently 
sacrificed  to  the  latter.  The  usual  result  of  glazing  is  found 
in  an  increase  of  8  to  10  per  cent,  in  the  tensile  strength,  but 
a  diminution  of  elasticity  to  the  extent  of  8  to  10  per  cent. 
With  supercalendered  magazine  papers,  the  high  surface 
is  imparted  for  the  sake  of  the  illustrations  w^hich  are  pro- 
duced by  methods  requiring  it.  The  addition  of  consider- 
able quantities  of  clay  or  mineral  substances  improves  the 
finish,  so  that  the  question  of  the  relation  of  glazing  to 
strength,  surface,  and  loading  is  one  which  affects  the 
subject  of  deterioration  of  paper  very  materially.  With 
writing  paper  the  false  standard  of  an  "  attractive  "  appear- 
ance is  almost  universally  accepted  by  the  public  as  the 
basis  of  purchase  without  any  reference  to  actual  quality. 

Mineral  Suhstances. — China  clay,  sulphate  of  lime,  agalite 
and  other  inert  mineral  substances  are  important  factors 
in  lowering  the  quality  of  paper,  not  so  much  in  promoting 
the  actual  deterioration  of  paper  by  any  chemical  reaction 
with  the  fibres,  as  in  making  the  paper  less  capable  of 
resistance  to  the  influence  of  atmospheric  conditions  and 
ordinary  usage.  Clay  in  small,  well-defined  quantities 
serves  a  useful  purpose,  if  added  to  some  papers,  because 
it  favours  the  production  of  a  smooth  surface,  but  when 
the  combination  of  mineral  substances  is  carried  to  an 
extreme,  then  the  result  from  the  point  of  view  of  per- 
manence is  disastrous.    This  is  well   recognised  by  all 


THE  DETERIORATION  OE  PAPER 


235 


paper-makers,  and  in  Germany  the  limits  of  the  amount  of 
clay  or  loading  in  high-grade  paper  have  been  rigidly  fixed. 
In  the  case  of  imitation  art  paper,  which  contains  25  to 
80  per  cent,  of  its  weight  of  clay,  the  strength  and  resist- 
ance of  the  sheet  is  reduced  to  a  minimum.  The  paper 
falls  to  pieces  if  slightly  damped,  the  felting  power  of  the 
fibres  being  rendered  of  no  effect  owing  to  the  weakening 
influence  of  excessive  mineral  matter.  This  paper  is  used 
chiefly  for  catalogues,  programmes,  circulars,  and  printed 
matter  of  a  temporary  and  evanescent  character,  and  so 
long  as  it  is  confined  to  such  objects  it  serves  a  useful  pur- 
pose, being  cheap,  and  suitable  for  the  production  of 
illustrations  by  means  of  the  half-tone  process  ;  but  its 
lasting  qualities  are  of  the  lowest  order.  The  addition  of 
10  per  cent,  of  any  mineral  substance  must  be  regarded  as 
the  maximum  allowance  for  papers  intended  for  permanent 
and  frequent  use. 

Coatuig  Material. — The  ingenious  method  for  producing 
an  absolutely  even  surface  on  paper  by  the  use  of  a  mix- 
ture of  clay  or  other  mineral  substance  and  an  adhesive 
like  glue  or  casein  brushed  on  to  the  surface  of  the  paper, 
is  responsible  for  many  of  the  complaints  about  the  papers 
of  the  present  day. 

The  sole  merit  of  this  substance  is  the  facility  with  which 
half-tone  process  blocks  can  be  utilised  for  the  purpose  of 
picture  production.  Beyond  this,  nothing  can  be  said. 
The  paper  is  brittle,  susceptible  to  the  least  suspicion  of 
dampness,  with  a  high  poHsh  which  in  artificial  light  pro- 
duces fatigue  of  the  reader's  eye  very  quickly,  heavy  to 
handle,  and  liable  to  fall  to  pieces  when  bound  up  in  book 
form. 

As  the  fibrous  material  is  completely  covered  by  mineral 
substances,  it  is  frequently  considered  of  secondary  imj^ort- 
ance,  with  the  result  that  the  ''value"  of  the  paper  is 


236 


THE  MANUFACTURE  OF  PAPER 


judged  entirely  by  the  surface  coating,  with  little  regard  to 
the  nature  of  the  body  paper.  In  such  cases,  with  an 
inferior  body  paper,  the  pages  of  a  book  very  quickly 
discolour,  and  the  letterpress  becomes  blurred. 


Analysis  of  a  Typical  Art  Paper. 


Per  Cent,  by 
Weight. 

Volume 
Composition 
per  Cent. 

Fibre 

77-0 

Fibre  . 

68-3 

Ash,  etc.  . 

22-0 

Ash 

12-0 

Air  space 

19-7 

100-0 

100-0 

Rosin. — The  presence  of  an  excess  of  rosin  is  a  well- 
known  factor  in  the  disintegration  of  the  paper,  even  when 
the  fibrous  composition  is  of  the  highest  order.  The 
decomposition  is  largely  due  to  the  action  of  light,  many 
experiments  having  been  made  by  Herzberg  and  others  to 
determine  the  nature  of  the  reactions  taking  place.  One 
of  the  chief  alterations  is  the  change  brought  about  in  the 
ink-resisting  qualities  of  the  paper. 

The  actual  character  of  the  chemical  reactions  as  far  as 
the  effect  on  the  fibre  is  concerned  is  not  accurately 
known.  The  degradation  of  a  hard-sized  rosin  paper  by 
exposure  to  strong  sunligbt,  for  example,  is  probably  due 
to  the  alteration  in  the  rosin  size,  and  not  to  any  material 
change  in  the  cellulose.  It  is  hardly  conceivable  that  in  a 
pure  rag  paper  sized  with  rosin  and  yielding  readily  to  ink 
penetration,  after  about  one  year's  exposure  to  light,  the 
cellulose  itself  had  undergone  any  chemical  changes  capable 
of  detection. 


THE  DETEEIOEATION  OF  PAPER 


237 


Gelatine. — Papers  properly  sized  with  gelatine  are  prefer- 
able to  those  sized  with  rosin  for  the  majority  of  books  and 
documents  preserved  under  normal  circumstances.  But 
the  nature  of  a  tub-sized  paper  may  be,  and  often  is, 
greatly  altered  by  unusual  climatic  conditions.  In  hot, 
damp  countries  papers  are  quickly  ruined,  and  high-class 
drawing  papers  sized  with  gelatine  often  rendered  useless. 
The  change  is  scarcely  visible  on  the  clean  paper,  and  is 
only  observed  when  the  paper  is  used  for  water-colour 
work,  the  colour  appearing  blotchy  in  various  parts  of  the 
sheet  where  the  gelatine  has  been  decomposed  by  the 
united  action  of  heat  and  damp. 

The  artist  is  frequently  compelled  in  such  cases  to  put  a 
layer  of  heavy  white  colour  on  the  sheet  of  paper  before 
proceeding  to  paint  the  picture. 

The  storage  of  books  under  favourable  conditions  has  a 
great  deal  to  do  with  the  permanence  of  the  paper,  and 
the  degradation  of  a  paper  in  relation  to  the  tub-sizing 
qualities  is  much  hastened  by  the  presence  of  moisture 
in  the  air. 

Starch,— The  same  is  true  of  starch,  which  is  largely 
employed  as  a  binding  or  sizing  material  in  paper.  The 
degradation  of  gelatine,  starch,  and  similar  nitrogenous 
substances  is  due  to  the  action  of  organisms,  and  the 
following  experiments,  suggested  by  Cross,  are  interesting 
in  this  connection. 

If  strips  of  paper  are  put  into  stoppered  bottles  with  a 
small  quantity  of  warm  water  and  kept  at  a  temperature 
of  about  80°  F.,  fungus  growths  will  be  noticed  on  some  of 
them  after  the  lapse  of  fourteen  days.  Kag  papers  sized 
with  gelatine  will  show  micro-organisms  of  all  kinds.  A 
pure  cellulose  paper,  like  filter  paper,  will  not  produce  any 
such  effects.  The  result  in  the  first  case  is  due  to  the 
nitrogenous  substance,  viz.,  the  gelatine  used  in  sizing, 


238 


THE  MANUFACTUEE  OF  PAPER 


since  the  two  papers  are  identical  as  far  as  the  cellulose 
fibres  are  concerned.  High-class  wood  pulp  papers,  unless 
sized  with  gelatine,  would  not  show  similar  results.  The 
action  of  the  organisms  upon  the  nitrogenous  material  by  a 
process  of  hydrolysis  is  in  the  direction  of  the  production 
of  soluble  compounds  allied  to  the  starch  sugars  capable  of 
being  assimilated  by  organisms. 

The  cellulose  of  esparto  and  straw  are  readily  attacked, 
and  it  is  on  this  account  that  the  tissues  of  the  various 
straws  are  digested  more  or  less  when  eaten  by  animals. 
It  is  for  this  reason  that  the  celluloses  from  straw  and 
esparto  are  inferior  to  the  cotton  cellulose  in  producing  a 
paper  likely  to  be  permanent. 

Chemical  Residues. — The  necessity  for  manufacturing  a 
pure  cellulose  half-stuff  is  fully  recognised  by  paper- 
makers.  This  was  not  the  case  in  the  early  days  of  the 
manufacture  of  wood  pulp,  for  it  is  a  matter  of  common 
experience  that  many  of  the  books  printed  on  wood  pulp 
paper  between  1870  and  1880  are  in  a  hopeless  condition, 
and  it  is  quite  easy  to  find  books  and  periodicals  of  that 
date  the  pages  of  which  crumble  to  dust  when  handled. 
This  serious  defect  has  been  proved  to  be  due  to  the  pre- 
sence of  tracer  of  chemicals  used  in  manufacture  which 
have  not  been  thoroughly  removed  from  the  pulp. 

The  precautions  necessary  in  bleaching  pulp  by  means 
of  chloride  of  lime,  in  order  to  prevent  (1)  any  action 
between  the  fibre  and  the  calcium  hypochlorite,  '2)  the 
presence  of  residual  chlorine  or  soluble  compounds  derived 
from  it,  and  (3)  the  presence  of  by-products  arising  from 
the  use  of  an  antichlor,  are  also  well  known  to  paper 
makers.  The  subject  has  been  closely  studied  by  chemists, 
who  have  shown  that  the  deterioration  of  many  modern 
papers  may  be  ascribed  to  carelessness  in  bleaching. 

The  questions  relating  to  the  chemical  residues  of  paper 


THE  DETERIOEATION  OF  PAPEE  239 


can  only  be  adequately  dealt  with  by  a  discussion  of  actual 
cases  which  arise  from  time  to  time.  There  are  certain 
conditions  in  manufacture,  common  to  all  papers,  which 
may  give  rise  to  the  presence  of  chemical  residues,  of 
which  two  have  already  been  mentioned. 

The  acidity  of  papers  is  frequently  quoted  as  an  instance. 
It  is  true  that  the  presence  of  free  acid  in  a  paper  is  most 
undesirable,  as  it  seriously  attacks  the  cellulose,  converting 
it  into  an  oxidised  form.  This  in  course  of  time  renders 
the  paper  so  brittle  as  to  destroy  its  fibrous  character. 

The  change  is  brought  about  by  the  acid,  which  itself 
suffers  no  material  alteration,  so  that  the  process  of  deterio- 
ration is  continued  almost  indefinitely  until  the  cellulose 
is  completely  oxidised.  Most  papers,  however,  show  an  acid 
reaction  when  tested  with  litmus,  the  usual  reagent  employed 
by  those  not  familiar  with  the  proper  methods  of  testing 
paper.  All  papers  which  have  been  treated  with  an  excess 
of  alum  for  sizing  purposes  would  show  an  acid  reaction 
with  litmus  without  necessarily  containing  any  free  acid. 

The  presence  of  iron  is  undesirable,  particularly  in  photo- 
graphic papers,  and  since  cellulose  has  a  remarkable  affinity 
for  iron,  the  conditions  of  manufacture  which  tend  to  leave 
iron  in  the  pulp  have  to  be  taken  into  consideration.  The 
presence  of  minute  quantities  of  iron  in  the  form  of 
impurities  must  not  be  confused  with  the  presence  of  iron  in 
large  quantities  derived  from  the  toning  and  colouring  of 
paper  by  means  of  iron  salts. 

The  fading  of  colour  is  frequently  observed  when  coloured 
papers  are  tested  on  boxboards,  particularly  those  made  of 
straw.  This  fading  may  often  be  traced  to  the  presence  of 
alkali  in  the  straw  board  which  has  not  been  completely 
removed  in  the  process  of  manufacture. 

The  blurring  of  letterpress  is  a  defect  which  often  occurs 
with  printing  papers  made  of  chemical  wood  pulp.    The  oil 


240 


THE  MANUFACTURE  OF  PAPER 


in  the  ink  seems  to  separate  out  on  either  side  of  the  letter, 
producing  a  discoloration.  In  such  cases  the  paper  itself 
frequently  exhibits  an  unpleasant  smell. 

These  defects  are  usually  determined  by  the  presence  of 
traces  of  sulphur  compounds  in  the  paper  resulting  from 
incomplete  washing  of  the  pulp  in  manufacture.  The 
presence  of  sulphur  compounds  sometimes  associates  itself 
with  papers  which  have  been  coloured  by  means  of  ultra- 
marine, which  in  presence  of  alum  is  slightly  decomposed 
by  the  heat  of  the  drying  cylinders. 

Some  knowledge  of  the  effect  of  chemical  residues  in 
paper  is  important,  not  only  in  regard  to  the  deterioration 
which  takes  place  in  the  fibre  itself,  but  also  in  relation  to 
the  fading  of  the  ink  which  is  used.  The  subject  of  the  ink 
has  received  much  attention  from  chemists  on  account  of 
the  serious  difficulties  which  have  been  experienced  by  State 
departments  in  various  countries. 

The  United  States  Department  of  Agriculture  have  devised 
certain  methods  for  ascertaining  the  suitability  of  stamping 
ink  used  by  the  Government  and  suggest  the  qualities 
desirable  in  such  an  ink.  The  ink,  first  of  all,  must  produce 
an  indelible  cancellation ;  that  is,  it  must  be  relatively 
indelible  as  compared  with  the  ink  used  for  printing  the 
postage  stamps.  The  post-mark  made  with  the  ink  must 
dry  quickly  in  order  that  the  mail  matter  may  be  handled 
immediately  without  any  blurring  or  smearing  of  the  post- 
mark. 

Both  this  property  and  the  property  of  the  indelibility 
involve  the  question  of  the  rate  at  which  the  ink  penetrates 
or  is  absorbed  by  the  fibre  of  the  paper.  A  satisfactory  ink 
does  not  harden  or  form  a  crust  on  the  ink-jDad  on  exposure 
to  air.  There  must  be  no  deposition  of  solid  matter  on  the 
bottom  of  the  vessel  in  which  the  ink  is  stored,  and  the  pig- 
ments on  which  the  indelibility  of  the  ink  depends,  if 


THE  DETEEIOKATION  OF  PAPER 


241 


insoluble,  must  not  settle  out  in  such  a  way  as  to  make  it 
possible  to  pour  off  from  the  top  of  the  container  a  portion 
of  the  ink  which  contains  little  or  none  of  the  insoluble 
pigment  or  pigments. 

Colour. — If  the  subject  of  deterioration  of  paper  is  to  be 
considered  in  its  broadest  sense  as  including  changes  of  any 
kind,  the  fading  of  colour  must  be  taken  into  account.  The 
use  of  aniline  dyes  which  are  not  fast  to  light  results  in  a 
loss  of  colour  in  paper  just  as  with  textiles,  and  the  fading 
may  be  regarded  as  a  function  of  the  dye  and  not  as  arising 
from  its  combination  with  the  paper. 

The  gradual  fading  of  some  dyes,  however,  and  of  many 
water-colour  pigments  may  be  traced  to  the  presence  of 
residual  chemicals  in  the  paper  and  to  the  presence  of 
moisture  in  an  atmosphere  impregnated  with  gaseous  or 
suspended  impurities.  In  fact  the  latter  is  a  greater  enemy 
to  permanence  of  colour  than  light,  since  it  has  been  proved 
by  experiment  that  most  colours  do  not  fade  when  exposed 
to  light  in  a  vacuum.  The  oxygen  of  the  air  in  combination 
with  the  moisture  present  is  the  principal  agent  in  bringing 
about  such  changes.  The  dulling  of  bronze,  or  imitation 
gold  leaf,  on  cover  papers  is  a  practical  illustration  of  this, 
though  this  can  hardly  be  quoted  as  an  instance  of  actual 
deterioration  of  the  paper. 

The  maintenance  of  the  original  colour  can  only  be 
assured  by  the  careful  selection  of  pure  fibrous  material, 
the  use  of  fast  dyes,  and  the  preservation  of  the  book  or 
painting  from  the  conditions  which  favour  the  fading  as 
described  above.  For  common  papers  such  precautions 
become  impossible,  but  for  water-colour  drawings  and 
valuable  papers  they  are  essential. 

The  demand  for  an  abnormally  white  paper  is  indirectly 
the  cause  of  deterioration  in  colour,  but  in  this  case  the 
ultimate  effect  is  not  a  lading  but  a  discoloration  of  white 

p.  R 


242 


THE  MANUFACTUEE  OE  PAPER 


to  a  more  or  less  distinct  yellow  or  brown  colour,  due  to 
changes  in  the  fibre  which  may  often  be  traced  to  excessive 
bleaching.  In  this  case  the  fading  of  colour  is  directly  due 
to  deterioration  of  the  paper  itself,  and  may  occur  in 
celluloses  of  the  best  type.  With  lower-grade  papers  con- 
taining mechanical  wood  pulp  the  degradation  of  colour 
and  fibre  is  inevitable. 

Air  and  Moisture. — The  exact  effects  produced  on  paper 
freely  exposed,  or  in  books  as  ordinarily  stored,  depend  upon 
the  condition  of  the  atmosphere.  Pure  air  has  little  or  no 
action  upon  paper,  cellulose  being  a  remarkably  inert  sub- 
stance, and  even  in  impure  mechanical  wood  pulp,  if  merely 
exposed  to  pure  dry  air,  the  signs  of  decay  would  be  delayed 
considerably.  The  combined  action  of  air  and  moisture  is 
of  a  more  vigorous  character  in  promoting  oxidation  changes 
in  the  fibres,  or  a  dissociation  of  the  sizing  and  other 
chemical  ingredients  of  the  paper.  The  presence  of 
moisture  is,  indeed,  absolutely  essential  for  the  reaction  of 
some  substances  upon  one  another,  and  it  is  easy  to  show 
that  certain  chemical  compounds  can  be  left  in  ultimate 
contact,  if  absolutely  dry,  for  a  lengthened  period  without 
reacting,  but  the  addition  of  a  little  moisture  at  once  pro- 
duces chemical  union.  This  may  be  shown  by  a  simple 
experiment. 

Thus  a  piece  of  coloured  paper  which  may  be  bleached 
immediately  if  suspended  in  an  atmosphere  of  ordinary 
chlorine  gas  will  remain  unbleached  for  several  hours  if 
first  thoroughly  dried  in  an  oven  and  exposed  to  dry  gas. 

In  the  case  of  books  and  papers,  these  conditions  which 
promote  slow  disintegration  are  aggravated  by  the  presence 
of  impurities  in  the  air,  such  as  the  vapours  of  burning  gas, 
the  traces  of  acidity  in  the  atmosphere  of  large  manu- 
facturing towns,  the  excessive  dampness  and  perhaj)s  heat 
of  a  climate  favouring  the  growth  of  organisms.    All  these 


THE  DETEEIORATION  OF  PAPER  243 


factors  are  of  varying  degrees  in  different  places,  so  that 
the  deterioration  of  papers  does  not  proceed  in  the  same 
measure  and  at  the  same  rate  everywhere. 

Moisture.— It  may  not  be  out  of  place  to  discuss  some 
important  relations  between  moisture  and  the  physical 
qualities  of  a  sheet  of  paper.  A  paper  in  its  normal  con- 
dition always  contains  a  certain  proportion  of  water  as  one 
of  its  ingredients,  and  the  presence  of  this  moisture  has 
much  to  do  with  the  strength,  elasticity,  and  use  of  the 
paper,  the  absence  of  moisture  giving  rise  to  defects  and 
troubles  in  the  use  of  the  paper  which  to  a  certain  extent 
lower  its  commercial  value  and  deteriorate  it,  though  not 
perhaps  in  the  sense  of  permanent  degradation  of  quality. 

One  trouble  frequently  experienced  by  stationers  and 
others  is  that  known  as  wavy  edges.  The  edges  of  a  stack 
containing  sheets  of  paper  piled  upon  one  another  frequently 
twist  and  curl,  producing  what  are  known  as  wavy  edges. 
This  arises  from  the  fact  that  the  paper  when  manufactured 
was  deficient  in  natural  moisture,  and  that  when  stacked  it 
has  gradually  absorbed  moisture,  which  is  taken  up  first  by 
the  edges  exposed  to  the  air.  This  causes  unequal  expansion 
of  the  fibres  with  the  production  of  the  so-called  wavy  edges. 
The  only  remedy  in  such  cases  is  the  free  exposure  of  the 
sheets  before  printing,  so  that  the  moisture  is  absorbed 
equally  all  over  the  sheet.  The  cracked  edges  of  envelopes 
may  be  explained  by  reference  to  the  same  conditions. 
The  paper  is  worked  up  into  envelopes  in  an  over-dry 
condition,  and  the  fibres,  being  somewhat  brittle,  readily 
break  apart  from  one  another.  If  the  paper  is  kept  in 
stock  for  some  time  before  use  this  defect  can  be  very 
largely  remedied. 

With  supercalendered  papers  it  is  only  possible  to  obtain 
the  best  results  by  allowing  the  j^^i^per  to  stand  for  several 
days  after  making  before  it  is  glazed. 

R  2 


244 


THE  MANUFACTURE  OF  PAPER 


It  is  evident  from  these  few  examples  that  many  of  the 
troubles  experienced  by  printers  are  due  to  the  fact  that 
orders  for  paper  are  frequently  accompanied  by  an  instruc- 
tion for  immediate  delivery,  under  which  circumstances  it  is 
impossible  to  obtain  the  best  results.  The  expansion  of 
papers  used  for  lithography,  and  the  bad  register  frequently 
seen  in  colour  work,  may  be  explained  by  reference  to  the 
behaviour  of  the  individual  fibres  towards  moisture.  The 
expansion  is  usually  greater  in  one  direction  of  the  paper 
than  in  the  direction  at  right  angles  to  it,  and  this  is  due  to 
the  fact  that  fibres  have  a  greater  ratio  of  expansion  in  the 
diameter  than  in  the  length. 

The  behaviour  of  papers  when  damped  is  a  peculiarity 
well  known  to  paper-makers  and  printers.  For  certain 
purposes  it  is  desirable  that  paper  should  not  show  any 
material  alteration  when  damped,  since  any  expansion  of 
the  sheet  is  liable  to  throw  the  printing  out  of  "  register." 
The  liability  of  papers  to  such  stretch  or  expansion  is 
largely  minimised  by  careful  manipulation  of  the  pulp 
during  the  process  of  beating,  and  also  by  a  proper  regula- 
tion of  the  web  of  paper  as  it  passes  from  the  wet  end  of 
the  paper  machine  over  the  drying  cylinders  to  the 
calenders.  The  paper  which  fulfils  the  necessary  qualifica- 
tions as  to  a  minimum  stretch  is  prepared  from  pulp  which 
has  not  been  beaten  for  too  long  a  period,  so  that  the  pulp 
obtained  is  fairly  light  and  bulky.  By  this  means  the 
expansion  of  the  fibres  takes  place  in  the  sheet  itself  with- 
out making  any  material  alteration  in  its  size.  That  is  to 
say,  as  the  sheet  of  paper  is  fairly  open,  there  is  sufficient 
room  for, expansion,  which  thus  takes  place  with  the  least 
alteration  of  the  total  area  of  the  sheet.  The  paper  which 
is  allowed  to  shrink  on  the  machine  during  the  process  of 
drying,  without  undue  tension,  usually  exhibits  a  minimum 
amount  of  expansion  subsequently  in  printing. 


THE  DETERIORATION  OF  PAPER 


245 


It  is  important  to  notice  that  the  expansion  of  paper  is 
different  for  the  two  directions,  that  is  for  the  machine  and 
cross  directions. 

This  arises  from  the  fact  that  in  the  machine-made  paper 
the  greater  proportion  of  the  fibres  point  in  the  direction  of  the 
machine  while  the  paper  is  being  made.  In  consequence  of 
this  the  expansion  of  the  paper  is  greatest  in  what  is  known  as 
the  cross  direction  of  the  paper,  that  is,  in  the  direction  at 
right  angles  to  the  flow  of  the  pulp  along  the  machine  wire. 

This  is  to  be  explained  by  reference  to  the  behaviour  of 
fibres  when  damped  or  brought  into  contact  with  an  excess 
of  water.  The  question  of  the  exact  changes  in  the  dimen- 
sions of  a  fibre  due  to  absorption  of  water  has  been  dealt 
with  in  an  interesting  manner  by  Hohnel.  He  points  out 
that  the  well-known  peculiarity  of  the  shrinkage  of  ropes 
which  have  been  lying  in  the  water  can  be  explained  by  an 
examination  of  the  behaviour  of  the  single  fibres.  He 
relates  in  detail  the  experiment  which  can  be  carried  out 
for  the  exact  observation  of  the  fibres  when  in  contact  with 
water.  A  dry  fibre  when  soaked  in  water  appears  to  become 
20  to  30  per  cent,  greater  in  diameter,  whereas  in  length  it 
is  usually  only  increased  by  one-tenth  per  cent. 

The  method  adoj^ted  by  Hohnel  was  to  place  a  fibre  of 
convenient  length  on  a  glass  slip  down  the  centre  of  which 
was  a  fine  narrow  groove  capable  of  holding  water,  so  that 
the  fibre  could  be  wetted.  Over  the  fibre  was  a  cover  glass 
with  a  small  scale  marked  on  it.  The  loose  end  of  the 
fibres  passed  over  a  small  roller  and  was  stretched  by  a 
light  weight.  The  movements  of  the  fibre  were  measured 
by  means  of  an  eye-piece  micrometer. 

In  this  way  it  is  possible  to  determine  alterations  in 
length  to  within  0*005  per  cent.,  and  this  variation  can  be 
directly  seen  under  the  microscope. 

Hohnel  observes  in  his  account  of  the  experiments  that 


246 


THE  MANUFACTUEE  OF  PAPER 


all  fibres  become  thicker  when  wetted,  that  vegetable  fibres 
are  more  susceptible  than  animal  fibres. 

Animal  fibres  expand  about  10  to  14  per  cent,  in  diameter, 
but  vegetable  fibres  as  much  as  20  per  cent.,  as  shown  in  the 
following  table : — 


Animal  Fibre. 

Per  Cent. 

Vegetable  Fibre. 

Per  Cent. 

Human  hair . 

10-67 

New  Zealand  flax 

20-0 

Angora  wool . 

10-2 

Aloe  hemp 

25-8 

Alpaca  wool  . 

13-7 

Hemp 

22-7 

Tussah  silk  . 

11-0 

Cotton 

27-5 

The  reverse  is  the  case  when  the  expansion  of  the  fibres 
in  regard  to  length  is  considered,  since  animal  fibres  expand 
0'50  to  1*00  per  cent,  of  their  length,  and  vegetable  fibres 
only  0-05  to  0*10  per  cent. 

The  maximum  amount  of  expansion  in  the  case  of  the 
vegetable  fibres  is  obtained  by  gently  breathing  upon  them 
rather  than  by  the  use  of  an  excess  of  water. 

These  figures  are  important  as  explaining  many  of  the 
peculiar  characteristics  of  vegetable  and  animal  fibres. 
Advantage  is  taken  of  the  greater  expansion  of  the  latter 
in  the  manufacture  of  instruments  for  the  measurement 
of  moisture,  such  as  the  hair  hygrometer,  in  which  t)ie 
elongation  of  a  stretched  hair  registers  the  variation  in 
the  moisture  of  the  atmosphere. 

Quality  of  Book  Papers. — The  Committee  of  the  Society 
of  Arts  in  dealing  with  the  evidence  as  to  the  permanence 
of  finished  papers  suggest  the  following  classification  as 
indicating  the  desired  standards  of  quality: — 

(A)  Classification  as  to  Fibees. 

A.  Cotton,  fiax,  and  hemp. 

B.  Wood  celluloses,  (a)  sulphite  process,  and  (b)  soda  and 

sulphate  process. 


THE  DETERIORATION  OF  PAPER  247 


C.  Esparto  and  straw  celluloses. 

D.  Mechanical  wood  pulp. 

The  Committee  find  little  fault  with  the  Principles  which 
govern  the  trade  in  the  manufacture  of  high-class  papers, 
and  limit  the  result  of  their  investigation  to  the  suggestion 
of  a  normal  standard  of  quality  for  book  papers  required 
in  documents  of  importance  according  to  the  following 
schedule : — 

Fibres. — Not  less  than  70  per  cent,  of  fibres  of  Class  A. 
Sizing. — Not  more  than  2  per  cent,  rosin,  and  finished 

with  the  normal  acidity  of  pure  alum. 
Loading. — Not   more  than  10  per  cent,  total  mineral 

matter  (ash). 

With  regard  to  written  documents,  it  must  be  evident 
that  the  proper  materials  are  those  of  Class  A,  and  that  the 
paper  should  be  pure,  sized  with  gelatine  and  not  with 
rosin.  All  imitations  of  high-class  writing  papers,  which 
are  in  fact  merely  disguised  printing  papers,  should  be 
carefully  avoided. 

These  recommendations  are  good  as  far  as  they  go,  but 
in  order  to  establish  the  proper  standards  of  quality  some 
specifications  must  be  laid  down  with  regard  to  the  strength 
of  the  paper  and  its  physical  properties,  together  with  a 
reference  to  the  use  for  which  the  paper  is  intended.  The 
physical  condition  of  the  paper  itself  apart  from  the  nature 
of  the  fibre  has  much  to  do  with  its  resistance  to  wear  and 
tear,  and  this  is  easily  proved  by  comparing  modern  book 
papers  made  from  esparto  with  book  papers  of  an  earlier 
date  made  from  the  same  material. 

The  only  ofiicial  schedule  of  requirements  in  relation  to 
public  documents  is  that  issued  by  the  Stationery  Ofiice. 

The  details  set  out  relate  chiefly  to  questions  of  weight  and 
strength,  the  limits  being  exjDressed  in  definite  form  and  not 
allowing  much  margin  for  variation  in  respect  of  strength 


248 


THE  MANUFACTURE  OF  PAPER 


or  fibrous  constituents.  Mechanical  wood  pulp  is  excluded 
in  all  papers  except  common  material  as  stated  in  the 
schedule.  The  papers  required  for  stock  are  divided  into 
twelve  classes.  In  each  class  the  trade  names  of  various 
sized  papers  are  given,  the  size  of  the  sheet  and  the  weight 
of  the  ream,  and,  where  required,  any  special  characteristics 
are  set  out.    The  schedule  is  as  follows : — 

Class  1.    Hand-made  or  Mould-made. 

General  Specification.  —  Hand-made  or  mould-made. 
Animal  tub-sized.  C'  Hand-made  "  or  "  Mould-made  "  to  be 
marked  on  the  wrapper.) 

Where  special  water-marking  is  required  mould  will  be 
supplied  by  the  Stationery  Office  for  those  papers  made  by 
hand. 

Class  2.    Writi7igs,  Air-dried. 

General  Specification. — Plate  rolled.  Machine  made. 
Animal  tub-sized.  Air-dried.  (Must  bear  ink  after 
erasure.) 

Note. — The  mean  breaking  strain  and  mean  stretch 
required  are  given  for  each  paper.  The  figures  represent 
the  mean  of  the  results  obtained  for  both  directions  of  the 
sheet,  and  are  calculated  on  a  strip  of  paper  five-eighths  of 
an  inch  wide  and  having  a  free  length  of  seven  inches 
between  the  clips. 

Class  3.    Writings,  Ordinary. 

General  Specification. — Eolled.  Machine-made.  Animal 
tub-sized. 

Class  4.    Writings,  Coloured. 

Specification. — Highly  rolled.  Machine-made.  Animal 
tub-sized. 


THE  DETERIORATION  OF  PAPER 


249 


Class  5.    Blotting  Paj)ers. 
Siyecification. — All    rag.     Machine-made.     Free  from 
loading. 

Class  6.    Printing  and  Lithographic  Papers. 

General  Specification. — Rolled.  Machine-made.  Engine- 
sized.    Loading  not  to  exceed  15  per  cent. 

Class  7.    Coloured  Printings. 

General  Specification. — Rolled.  Machine-made.  Engine- 
sized. 

Class  8.    Copying  and  Tissue  Papers. 

Specification.  —  Machine-made.  Free  from  loading. 
(Copying  papers  are  required  to  give  three  good  copies.) 

Class  9.    Brown  Papers,  Air-dried. 

Specification. — Air-dried.  Machine-made. 

Note. — The  mean  breaking  strain  and  mean  stretch 
required  are  given  for  each  paper.  The  figures  represent 
the  mean  of  the  results  obtained  for  both  directions  of  the 
sheet,  and  are  calculated  on  a  strip  of  paper  two  inches 
wide  and  having  a  free  length  of  seven  inches  between  the 
clips. 

In  the  case  of  papers  indicating  a  larger  breaking  strain 
than  the  minimum  required,  a  proportional  increase  in  the 
stretch  must  also  be  shown. 

Class  10.    Brown  Paper,  Cylinder -dried. 

General  Specification. — Machine-made. 

Note. — The  mean  breaking  strain  required  is  given  for 
each  paper.  The  figures  represent  the  mean  of  the  results 
obtained  for  both  directions  of  the  sheet,  and  are  calculated 
on  a  strip  of  paper  two  inches  wide  and  having  a  free  length 
of  seven  inches  between  the  clips. 


250 


THE  MANUFACTUEE  OF  PAPER 


Class  11.  Smallhands. 
General  Specification. — Machine-made.  Engine-sized. 

Class  12.    Buff  Papers. 

Specification. — Highly  finished  both  sides.  Machine-made. 
Hard  engine-sized. 

Mechanical  wood  pulp  must  not  be  used  in  the  manufac- 
ture of  any  papers,  with  the  exception  of  engine-sized 
coloured  printings,  and  buff  papers,  where  an  addition  up 
to  25  per  cent,  will  be  allowed. 

All  animal  tub-sized  papers  are  required  to  be  as  far  as 
possible  free  from  earthy  matter;  and,  except  where 
specially  stated,  the  amount  of  loading  added  to  other  papers 
must  not  exceed  6  per  cent. 

When  sulphite  or  soda  pulps  are  used,  either  separately 
or  conjointly,  in  the  manufacture  of  printing  papers,  the 
quantity  of  neither  material  shall  separately  exceed  50  per 
cent. 

The  most  comj^lete  specification  as  to  the  requirements 
for  standard  papers  is  that  published  by  the  Paper  Testing 
Institute  in  Germany,  and  used  as  the  basis  of  most  con- 
tracts, at  least  for  public  and  official  documents. 

Standards  of  Quality  in  Germany. — The  classification  of 
pajDers  according  to  the  raw  materials  used  and  the  nature  of 
the  finished  paper  is  very  complete.  The  classification  is 
made  under  three  headings  :  (A)  Raw  Material;  (B) 
Strength;  (C)  Uses. 

(A)  Classification  according  to  Material. 

(1)  Paper  made  from  rags  only  (linen,  hemp,  and  cotton). 

(2)  Paper  made  from  rags  with  a  maximum  of  25  per 
cent,  of  cellulose  from  wood,  straw,  esparto,  maiiila,  etc.,  but 
free  from  mechanical  wood  pulp. 


THE  DETERIOEATION  OF  PAPER  251 

(3)  Paper  made  from  any  fibrous  material,  but  free  from 
mechanical  wood  pulp. 

(4)  Paper  of  any  fibrous  material. 


(B)  Classification  according  to  Strength. 


Class 

1. 

2. 

3. 

4. 

5. 

6. 

Mean  tearing  length  in 

metres  .... 

;,ooo 

5,000 

1,000 

3,000 

2,000 

1,000 

Elasticity  per  cent. 

4 

a-5 

3 

2-5 

2 

l-o 

Kesistance     to  folding 

(Schoppers'  method, 

number  of  foldings)  . 

1<)0 

190 

80 

40 

20 

3 

The  tests  for  tearing  length,  resistance  to  folding,  elas- 
ticity, etc.,  are  made  in  air  showing  relative  humidity  of 
65  per  cent.  The  calculations  for  tearing  length  are  made 
on  strips  of  paper  dried  at  100°  C. 


(C)  Classification  according  to  Use. 


Weight  of 

w 

CO 

Uses. 

Fibre. 

Strength. 

Size  of  Sheets. 

Q 

Class. 

Class. 

Cm. 

1,000 

1  Sq. 

Sheets. 

Metre. 

Kg. 

Grms. 

1 

Writing  papers  for  im- 

portant documents  . 

1 

1 

33    X  42 

15 

Paper  for  State  docu- 

ments 

1 

1 

2G-5  X  42 

12 

2 

Paper  for  registers,  ac- 
count   boolvs,  and 

ledgers — 

(a)  First  quality  . 

1 

2 

33    X  42 

14 

Ih)  Second  quality 

1 

3 

33    X  42 

13 

3 

Documents  intended  to 

be  preserved  longer 

than  ten  years — 

iji^  Foolscap  paper 

2 

3 

33    X  42 

13 

Letter  paper 

(quarto  size) 

2 

3 

2r)-.5  X  42 

10-4 

252  THE  MANUFACTURE  OF  PAPER 

(C)  Classification  according  to  Use — continued. 


Uses. 


Documents  intended  to 
be  preserved  longer 
than  ten  years — ctm- 
tinued. 
Letter  paper 

(octavo  size) 
Duplicating  paper  . 
(h')  Official  writing 
paper 

Paper  for  documents  of 
lesser  importance — 
(<■/)  Foolscap  paper 
Letter  paper 

(quarto  size) 
Letter  paper 
(octavo  size) 
(/>)  Official  w^riting 
paper 

Envelopes  and  wrap- 
pers— 
(<■/)  First  quality  . 
(b)  Second  quality 
Writing  paper  of  me- 
dium quality  . 
Covers  for  documents — 
(a)  That  required  for 
frequent  use  . 


(ft)  For  other  purposes 


Printing  paper — 

(«)  For  important 

printed  matter 
(ft)  For  less  important 

printed  matter 
(r)  For  common  use 


Fibre. 
Class. 


Strength. 
Class. 


4 

3 
o 

5—6 


Tearing 
length 
2,500 
Elasticity 
3-5  % 
Tearing 
length 
2,500 
Elasticity 
2-5  % 


4 

-)— 6 


Size  of  Sheets. 
Cm. 


26-5  X  21 
38     X  42 

33    X  42 


33  X  42 
26-5  X  42 
26-5  X  21 
33    X  42 


36    X  47 


36    X  47 


Weight  of 


1,000 
Sheets. 
Kg. 


5-2 

7 

13 


12 
9-6 
4-8 

12 


81-2 


42  3 


CHAPTER  XIII 


BIBLIOGRAPHY 

ANALYSIS,  TECHNOLOGY,  ETC. 

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1905. 

Arabol  Manufacturing  Co.  Theory  and  Practice  of  the  Sizing  of 
Paper.    New  York,  8°,  1895. 

Behrens,  H. — Anleitung  zur  mikrochemischen  Analyse  der 
wichtigsten  Yerbindungen.  Heft  2.  Die  wichtigsten  Faserstoffe. 
Hamburg  unci  Leipzig,  1896. 

Beveridge,  J. — Paper-makers'  Pocket  Book.  London,  sm.  8°, 
1901. 

BouRDlLLAT,  E.  Die  Entfarbung  und  das  Bleichen  der  Hadern. 
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CoRPUT,  E.  Van  den. — De  la  fabrication  du  papier  au  point  de  vue 
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Cross,  C.  F.  and  Bevan,  E.  J. — A  Text-book  of  Paper-making. 
London,  sm.  8°,  1888. 

Ditto,  2nd  edition.  1900. 
Ditto,  3rd  edition.  1907. 

Cross  and  Bevan. — Manuel  de  la  fabrication  du  papier.  Traduit 
dela  2^  edition  Anglaise.    ParL.  Desmarest.  1902. 

Cross,  Bevan,  Beadle  and  Sindall. — The  C.B.S.  Units  :  a  Book 
on  Paper  Testing.  1904. 

Deterioration  of  Paper. — Society  of  Arts  Eeport.  1898. 

Engelhardt,  B.  Hypochlorite  und  electrische  Bleiche  (Tech- 
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Engels,  J.  A. — Ueber  Papier  und  einige  andere  Gegenstande  der 
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254 


THE  MANUFACTUEE  OF  PAPER 


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edition,  by  J.  Hiibner.    London,  8°,  1901. 

FiNKENER. — Ueber  die  quantitative  Bestimmung  des  Holzschliffes 
in  Papier  nach  Goddefroy  und  Ooulon.  1892. 

Flatters. — Microscopical  Research.  1906. 

Griffin,  E.  B.  and  Little,  A.  D. — The  Chemistry  of  Paper-making, 
with  Principles  of  General  Chemistry.    New  York,  8°,  1894. 

Hassak. — Wandtafeln  fiir  Warenkunde  u.  Mikroskopie.  1904. 

Haywood,  J.  K. — Arsenic  in  Papers  and  Fabrics.  1904.  (U.S.A. 
Department  of  Agriculture.) 

Herzberg,  W. — Mikrosk.    Untersuchung  des  Papiers.  1887. 

Herzberg,  W. — Papierpriifung.  Leitf.  bei  d.  Unters.  v.  Papier. 
1888. 

Ditto,  2nd  edition.  1902. 

Ditto,  3rd  edition.  1907. 
Herzberg,  W. — Paper  Testing  as  carried  out  in  the  Government 
Laboratory  at  Charlottenburg.    From  the  German,  by  P.  N.  Evans, 
London,  8°,  1892. 

Herzberg,  W. — Mitteilungen  aus  den  konigl.  technischeii  Yer- 
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HoHNEL,  F.  V. — Die  Mikroskopie  der  technisch.  verwendeten 
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Holbling,  v. — Die  Fabrikation  der  Bleichmaterialien.  Berlin. 

HoYER,  E — Le  papier ;  6tude  sur  sa  composition,  analyses  ot 
essais.    De  I'Allemand.    Paris,  8°,  1884. 

Hoyer-Kraft. — Die  Spinnerei,  Weberei  und  Papierfabrikation, 
4  Aufl.  1904. 

Jagenberg,  F. — Die  theorische  Leimung  fiir  endloses  Papier. 
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JoHAN^'^EN. — Mitteilungen  iiber  Mikrophotographic  von  Faser- 
stoffen  im  durchfallenden  und  auffallenden  Licht.  1906. 

Klemm,  p. — Papier  Industrie  Kalendor.    1898,  et  seq. 

Lauboeck. — tiber  die  Saugfahigkeit  der  Loschpapiere.  Mitteil- 
ungen des  k.k.  Technologischen  Gewerbe-Museums.    Wren,  1897. 

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BIBLIOGEAPHY 


255 


1884  bis  1903  enthalten  aus  der  Abteilung  fiir  Papierpriifung  die  im 
Jahrgang  1905,  dieses  Kalenders  verzeichneten  Arbeiten. 

Martens,  A. — Apparaten  ziir  Untersuchung  der  Festigkeitseigen- 
scbaften  von  Papier.  Konigl.  Techn.  Versuchsanstalten.  Mitteil- 
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Martens,  A. — Ueber  Druckpapier  der  Gegenwart.  Konigl.  Techn. 
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Martens,  A. — Untersuchung  Japanischer  Papiere.  Konigl.  Techn. 
Versuchsanstalten.  Mittheilungen.  Erganzungsheft.  No.  4.  8°,  1888. 

Martens  und  Gtjth. — Das  konigliche  Materialpriifungsamt  der 
technischen  Hochschule  Berlin  auf  dem.  Gelande  der  Domane  Dahlem 
beim  Bahnhof  Gross-Lichterfelde  West.    Berlin,  1904. 

Melnikoff,  N. — PriifuTig  von  Papier  und  Pappe  nebst  Adressbuch 
der  russischen  Papierfabriken.    Petershury,  1906. 

Muller,  L. — Die  Eabrikation  d.  Papiers  in  Sonderheit  d.  a.  d. 
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MUller  und  a.  Haussner. — Die  Herstellung  u.  Priifung  des 
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Ilolzschliffes  im  Papier.  1887. 

MuTH.  Die  Leimung  der  Pupierfaser  im  Hollander  und  die 
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und  Tintenpriifung.    Berlin,  1892. 

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d'un  aper9U  sur  Tetat  actuel  de  la  fabrication  du  papier.  Avec 
echantillons  de  papiers  colores.    Paris,  8°,  1863. 

Eejto,  a. — Anleitung  fur  Private  zur  Durchfiihrung  der  Papier- 
priifung.   Budapest,  1893. 

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256  THE  MANUFACTURE  OF  PAPER 


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Kirchner-Strohbach. — HoUander-Theorie.    Biberach.  1904. 

Klemm,  Dr.  p. — tiber  Papier.  Klimsch's  Graphische  Bibliothek 
Bd.  3  (Earbe  und  Papier  im  Druckgewerbe).  2  Teil.  Franhfiirt 
a.  M.  1900. 

Korschilgen  und  Selleger.— Technik  und  Praxis  der  Papier- 
fabrikation.   Berlin,  1906. 

Kraft,  M. — Grundriss  der  mechanischen  Technologic.  Abt.  ii. 
Spinnerei,  Weberei,  und  Papier-fabrikation.  2te  Aufl.  Wiesbaden, 
8°,  1895. 

Lenormand,  L.  S. — Manuel  du  fabricant  de  papier.  Paris, 
2  vols.,  18°,  1833. 

Ditto,  2nd  edition.  1834. 


264 


THE  MANUFACTURE  OF  PAPER 


Lenormand,  L.  S. — Nouveau  maniiel  complet  du  .  .  .  fabricant 
de  papiers  peints.    Nouv.  ed.  par  Yergnand.    Paris,  18°,  1854. 

Lenormand,  L.  S. — Handbuch  der  gesammten  Papier-fabrikation, 
2te  Aufl,  von  C.  Hartmann.    Weimar,  2  vols.,  12°,  1862. 

Meez. — BehandluDg  der  Papiermascbine. 

Meynier,  H. — Papier  und  Papier- Fabrikate.  Paris  Univ.  Exhibi- 
tion, 1867.    Austrian  Comm.  Berichte.    Heft  8.    8°,  1867. 

Mierzinski,  St. — Handbuch  d.  Papierfabrikation.   3  Bde.  1886. 

Muller,  F.  a.  L. — Die  Fabrikation  des  Papiers,  in  Sonderheit  der 
auf  der  Mascbinen  gefertigten,  etc.    3te  Aufl.    Berlin,  8°,  1862. 

Muller,  Dr.  L. — Die  Fabrikation  des  Papiers.    Berlin,  1877. 

Olmer,  Georges. — Du  papier  mecanique. 

Onfroy. — L'art  du  papier  et  le  papier  d' Arches.  1907. 

Paper-Making. — Paper-making,  by  the  Editor  of  the  Paper  Mills 
Directory,  London.    2nd  edition.    8°,  1876. 

Paper-Maker. — The  Paper-makers'  Handbook  and  Guide  to  Paper- 
making,  by  a  Practical  Paper-maker.    London,  sm.  8°,  1878. 

Paper-Manueacture.  —  Essays  by  a  Society  of  Gentlemen. 
No.  vi.,  pp.  21—27.  1717. 

Parkinson,  R. — Treatise  on  Paper,  with  Outline  of  Manufacture. 
1886. 

Ditto,  2nd  edition,  1896. 

Pa  YEN,  A.,  AND  OTHERS. — La  fabrication  du  papier  et  du  carton. 
3«ed.    Paris,  8°,  1881. 

Payen,  a.,  and  Vigreux,  L. — La  papeterie.  Etudes  sur  1' Exposi- 
tion de  1867.    Vol.  8.    8°,  1867. 

Pfau,  F. — Der  junge  Papierhandler.    Berlin,  1902. 

PiETTE,  L. — Manuel  .  .  .  de  papeterie  et  les  succedanes  (des 
chiffons).    Paris,  2  vols.,  8°,  1861. 

Planche,  G. — De  I'industrie  de  la  papeterie.    Paris,  8°,  1853. 

Planche,  G. — Der  Papierfabrikation.  Bearbeitet  von  C.  Hart- 
mann.   Weimar,  12°,  1853. 

Planche,  G.— Bericht  iiber  die  Reinigung  der  Stoffe  zur  Papier- 
fabrikation. Uebersetzt  und  vervollstandigt  durch  eine  chrono- 
logische  Skizze  der  Papier-Erzeugung  und  der  Verbesserungen  an  den 
Maschinen  zur  Reinigung  des  Papier-Stoffs  von  A.  Rudel.  Lei/pzig, 
8%  1862. 

Prouteaux,  a. — Practical  Guide  for  the  Manufacture  of  Paper  and 
(Paper)  Boards.  With  a  chapter  on  Wood  Paper  in  the  U.S.  by  H.  T. 
Brown.    Philadelphia,  8°,  1866. 


BIBLIOGRAPHY 


265 


Proijteaux,  a. — Guide  de  la  fabrication  du  papier  et  du  carton. 
Pan's,  12°,  1864. 

Eaab,  R. — Die  Schreibuiaterialen  und  die  gesamte  Papierindustrie. 
Ilamhurg,  1888. 

Reed,  A.  E. — Paper  Manufacture.  Society  for  the  Promotion  of 
Scientific  Industry.  Artisans'  Reports  upon  the  Vienna  Exhibition. 
8°,  1873. 

Richardson,  W.  II. — The  Industrial  Resources  of  the  Tyne  .  .  . 
[Paper].  1864. 

Schubert,  M. — Traitc  pratique  de  la  fabrication  de  la  cellulose. 
Trad.  p.  E.  Bibas.    Toile.  1893. 

Schubert,  M. — Die  Praxis  der  Papierfabrikation  mit  besond. 
Berucksichtigung  der  Stoffmischungen  und  deren  Calculationen. 
1897. 

Schubert,  M.— Die  Papierverarbeitung.    2  Bde.  1900—1901. 
Bd.  1.    Die  Kartonnagen  Industrie. 
Bd.  11.    Die  Buntpapierfabrikation. 

SiNDALL,  R.  W.  The  Manufacture  of  Paper  Pulp  in  Burma. 
Government  Press.    Rangoon,  1907. 

SiNDALL,  R.  W.— The  Manufacture  of  Paper.  1908.  Constable 
&  Co.  London. 

TwERDY,  E. — Papier  industrie.    Bcrichte.    Wien,  1873. 

Vachon,  M. — Les  arts  et  les  industries  du  j^apier.  France,  1871 
—1894. 

Valenta,  E.— Das  Papier,  seine  Herstellung,  Eigenschaften,  Prii- 
fung.  1904. 

Wanderley,  G. — Die  Papierfabrikation  und  Papierfabrikanlage. 
Leipzig,  1876. 

Watt,  A. — The  Art  of  Paper-making,  with  the  Recovery  of  Soda 
from  Waste  Liquors.    London,  sm.  8°,  1890. 

Weber,  R. — Paper  Industrie.    Vienna  Universal  Exhibition,  1873. 

Wehrs,  G.  F. — Vom  Papier,  den  vor  den  Erfindung  desselben 
iiblich  gewesenon  Schreibmassen  und  sonstigen  Schreibmaterialien. 
Halle,  8°,  1789. 

Winkler,  0. — Der  Papierkenner,  1887. 

PAPER,  SPECIAL  KINDS. 

Andes,  L.  E. — Papier- Speziaiitaten,  praktische  Anleitung  zur 
Herstellung.  1896. 


266 


THE  MANUFACTURE  OF  PAPER 


Andes,  L.  E. — Treatment  of  Paper  for  Special  Purposes.  Trans- 
lated from  German.  1907. 

Andes,  L.  E. — Die  Fabrikation  der  Papiermache  und  Papierstoff- 
Waren.    Lei^jzig,  1900. 

Andes,  L.  E. — Blattmetalle,  Bronzen  und  Metallpapiere,  deren 
Herstellung  und  Anwendung.    Wien,  sm.  8°,  1902. 

BoECK,  J.  P. — Die  Marmorirkunst  fur  Buchbindereen,  Buntpapier- 
fabriken.    Wien,  sm.  8°,  1880. 

Briquet,  M. — De  quelques  industries  nouvelles  dont  le  papier  est 
la  base.    Geneve,  1885. 

ExNEii,  W.  F. — Tapeten-und  Bunt-papier  Industrie.  Paris  Univ. 
Exhibition,  1867.    Austrian  Comm.  Berichte.    Heft  8.  1867. 

ExNEii,  W.  F.  —  Tapeten-und  Bunt-j^apier.  Vienna  Universal 
Exhibition,  1873.  Officieller  Ausstellungs-Bericht.  Heft  53.  8°, 
1873. 

FiCHTENBERG. — Nouveau  manuel  complet  du  f abricant  de  papiers  de 
fantaisie,  ^^apiers  marbres,  etc.    Paris,  1852. 

Heiiring,  R.— Guide  to  Varieties  and  Value  of  Paper.  1860. 

HoFMANN,  A.  W. — Report  on  Vegetable  Parchment  (Gaine's  Patent, 
No.  2834  of  1853).    London,  8^,  1858. 

Kaeppelin,  D. — Fabrication  des  papiers  peints.  Lacroix  E.,  Etudes 
sur  I'exposition  de  1867.    Vol.  1.    8°,  1867. 

Kaeppelin,  D. — Fabrication  des  papiers  peints.  1881. 

LiNDSEY,  G. — Pens  and  Papiermache.  Bevan,  G.  P.,  Brit.  Manu- 
facturing Industries  (iii.).    12°,  1876. 

Morton,  G.  H. — The  History  of  Paper-hangings,  with  Review  of 
other  Modes  of  M<iiral  Decoration.    Liverpool,  8°,  1875. 

Sanborn,  K.— Old  Time  Wall  Papers.  1905. 

Schmidt,  C.  H. — Die  Benutzung  des  Papiermache.  Weimar,  12°, 
1847. 

Schmidt,  C.  H. — Die  Papier-Tapetenfabrikation.  3te  Aufl.  Weimar, 
12°,  1856. 

Schmidt,  C.  H. — The  Book  of  Pajnermache  and  J apanning.  London, 
1850. 

Seeman,  Th. — Die  Tapete,  ihre  aesthetische  Bedeutung  u.  Techn. 
Darstellung,  sowie  kurze  Beschreibung  der  Buntpapierfabrik.  1882. 

SiLCOX. — Manufacture  of  Paper  Barrels.  Vienna  Exhibition,  1873. 
U.S.A.  Reports,  ii. 

Smee,  a. — Report  on  Vegetable  Parchment  (Gaine's  Patent,  No.  2834 
of  1853).    London,  8°,  1858. 


BIBLIOGEAPHY 


267 


Thon,  C.  F.  G. — Der  Fabrikant  bunter  Papier,  3te  Aufl.  Weimar, 
12°,  1844. 

Weichelt,  a. — Buntpapier  Fabrikation.    Berlin,  8°,  1903. 
Whiting  Paper  Co. — How  Paper  is  Made.    Holyoke,  Mass.,  32°, 
1893. 

WiNZER,  A.— Die  Beieitung  und  Benutzung  der  Papiermache  und 
ahnlicher  Kompositioneii,  3te  Aufl.    Weimar^  12°,  1884. 
Ditto,  4th  edition,  1907. 

WoOLNOUGii,  0.  W. — The  Whole  Art  of  Marbling,  as  ai:)plied  to 
Paper,  Book  Edges,  etc.    London,  8°,  1881. 

Wyatt,  Sir  M.   D. — Eeport  on  Paper-hangings.     Paris  Univ. 
Exhibition,  18G7.    Brit.  Comm.  Eeport,  Vol.  II.    8°,  1867. 

STATISTICS  AND  VARIOUS. 

Akessoist.  —  Lexikon    der    Papier-Industrie.  Deutsch-Englisch- 
Franzosisch,  2te  Aufl.  1903. 

Archer,  T.   C.  —  British    Manufacturing  Industries.     Vol.  15. 
Industrial  Statistics.  London. 

Barth,  E. — Arbeitsregeln  fur  Fabrikcn  mit  besondercr  Berucksich-  ♦ 
tigung  von  Papier-fabriken.   *KarisruJie,  1897. 

Baudisch,  J. — Einige  ins  Papierfach  schlagende  Berechnungen. 
Biberach.  1893. 

Dyson. — Mosely  Commission  Eeport.    Manchester,  1903. 

Ermel. — Eapport  sur  le  materiel  et  les  precedes  de  la  papeterie,  etc. 
Paris  Univ.  Exhibition,  1878.    Eapports.    Class  60.    8°,  1881. 

Foreign  Office,  No.  4  (1871). — Eeports  on  the  Manufacture  of 
Paper  in  Japan.    London,  fob,  1871. 

Geyer,  a. — Eegistry  of  Water-marks  and  Trade-marks.  Compiled 
from  the  American  Paper  Trade  (2nd  edition).    Neiv  York,  1898. 
Ditto,  5th  edition,  1903. 

Gratiot,  A. — Description  de  la  papeterie  d'Essonnes,  London 
International  Exhibition  of  1851,  Prospectuses  of  Exhibitors.  Vol.  2. 
8°,  1851. 

Krawany,  F. — Warte  der  Papier-Halbstoff-und  Pappenfabriken 
Oesterreich-Ungarns.  1905. 

Landgraf,  J. — Papier-Holzschliff  und  seine  Zollpolitische  Wurdi- 
gung.  Mannheim. 

LocKWOOD  &  Co.  —  American  Dictionary  of  Printing  and  Book- 
binding.   New  York,  1895. 


268 


THE  MANUFACTUEE  OF  PAPER 


LrDWiG,  Gr. — Trockengehalts-Tabellen.    Pima,  1897. 
MacNaughton",   J.  —  Factory   Book-keeping   for   Paper  Mills. 
1900. 

Mahrlen. — Papierfabrikation,  im  Konigr.  Wiirttemburg  (im  Jahre 
1860).    Stuttgart,  8°,  1861. 

Marr,  D. — Kosten  der  Betriebskraf te  bei  1 — 24  stiindiger  Arbeitszeit 
taglich  und  unter  Beriicksiclitigung  des  Aufwandes  fur  die  Heizung. 
Miinchen  u.  Berlin. 

Melnikoff,  N. — Lebrbuch  der  Papier-Holzscbliff,  Zellstoff  und 
Pappenfabrikation.    Petersburg,  1905. 

Melnikoee,  N. — Kleines  handbuch  Papierfabrikation.  Peterslurg, 
1906. 

Melnikoff,  N. — Gescbicbte,  Statistik  u.  Literatur  der  paper- 
industrie  nebst  russischen  Wasserzeichen.    Petersburg,  1906. 

MuNSELL,  J. — Chronology  of  Paper-making.  Albany,  8°,  1857. 
Ditto,  4tli  edition,  1870. 

MuNSELL,  J. — Chronology  of  the  Origin  and  Progress  of  Paper  and 
Paper-making.    Albany,  1876. 

MuNSELL,  J.  — Observations  Illustrative  of  the  Operation  of  the 
Duties  on  Paper.    London,  8°,  1836. 

MuNSELL,  J. — Materiel  et  precedes  de  la  papeterie,  etc.,  1889. 
Eapports  du  Jury.    Class  58.    8*^,  1889. 

Paris  Univ.  Exhibition. — PajDiers  points,  1889.  Rapports  du  Jury. 
Classe  21.    8°,  1891. 

Passerat,  a.  L. — Bareme  complet  pour  pa.peteries.  Paris. 

Patents. — Patent  Abridgments.  Class  96.  Patent  Office  Abstracts 
on  Paper-making.    From  1855  to  date. 

RouLHAC. — Papeterie.  Paris  Univ.  Exhibition,  1867.  Rapports  du 
Jury.    Classe  7,  sect.  1.    8°,  1868. 

Sampson,  J.  T.  —  Paper-staining.  Mansion  House  Committee. 
Artisans'  Reports,  Parish  Exhibition.    8°,  1889. 

Treasury. — Report  of  the  Excise  Commission.  1835. 

Vogel,  K.  —  Papier-industrie,  etc.,  Auf  der  Weltausstellung  in 
Chicago.  Chicago  Exhibition,  1893.  Austrian  Central  Committee. 
Officieller  Bericht.    Heft  iv.    8°,  1894. 

YoiGT,  Gr. — Papiergewichtstabellen.    Mersebiirg,  1894. 

Ward,  Sir  W.  —  Rej^ort  on  German  Paper-making  Industry. 
Parliamentary  Paper,  1905. 

Water-marks. — Water-marks  and  Trade-marks  Registry  (2nd  ed.). 
New  York,  16°,  1898. 


BT13liI;0,GJ^APJ,tY-  - ,  -  -    r  >  ^  ^'  ^  -  269 


WOOD  PULP  AND  PULP  WOOD. 

British  and  Colonial  Printer. — History  of  Wood  Puli?.  Vol.  8. 
1882. 

Dunbar. — Wood  Pulj^  and  Wood  Pulp  Papers. 
FiTTiCA,  Dr.  F. — Geschichte  der  Salfitzellstoff-fabrikation.  Leipzig, 
1901. 

FiTTiCA,  Dr.  F. — Forestry  and  Forest  Products.  [Edinburgh 
Forestry  Exhibition.  1884.] 

GoTTSTEiN. — Holzzellstoff  in  seiner  Anwendung  fur  die  Papier  und 
Textil-Industrie  und  die  bei  seiner  Herstellung  entstehenden  Abwasser. 
1904. 

Griffin,  M.  L. — Sulphite  Processes.  American  Society  C.  E.  417. 
1889. 

Harper,  W. — Utilisation  of  Wood  Waste  by  Distillation.  U.S.A., 
1907. 

Harpf,  a. — Die  Erzeugung  von  Holzschliff  und  Zellstoff.  IFrm, 
1901. 

Harpf,  A. — Fliissiges  Schwefeldioxyd.    Stnttf/art,  1901. 

Hubbard. — Utilisation  of  Wood  Waste.  1902. 

Johnson,  G.— Wood  Pulp  of  Canada.    1902—08.  Yearly. 

MiciiAELis,  O.  E. — Lime  Sulphite  Fibre  Manufacture  in  the  United 
States.  With  Eemarks  on  the  Chemistry  of  the  Processes,  by  M.  L. 
Griffin  (excerpt).    Neiu  YorJc,  8°,  1889. 

Phillips,  S.  C— Uses  of  Wood  Pulp.  1904. 

EosENHEiM,  G.  M. — Die  Holzcellulose.    Berlin,  1878. 

Schubert,  M. — Die  Holzsto:ff  oder  Holzschliff-fabrikation.  1898. 

Schubert,  M.— Die  Cellulosefabrikation  (Zellstoff-fabrikation). 
Praktisches  Handbuch  fur  Papier-u.  Cellulose-techniker.  1906. 

SiNDALL,  E.  W.— The  Sampling  of  Wood  Pulp.    London,  8°,  1901. 

Yeitch,  L.  p.— Chemical  Methods  for  Utilising  Wood.  U.S.A. 
Department  of  Agriculture.  1907. 

Yeitch,  L.  P.— Wood  Pulp,  Uses  of.  U.S.A.  Consular  Eeports, 
vol.  xix. 


Banks  and  Crate.— Pulpwood  Problems.  Letters  to  the  (7Zo&e, 
Toronto,  Canada.  1907. 

Gamble,  J. — Lidian  Timbers. 

Graves.— The  Woodsman's  Handbook.  U.S.A. 

Pinchott,  G.— Forestry  Primer.    U.S.A.,  1900. 


270   .\  -  :,'?:hp  MA^T^FAC^TTOJ^  of  papee 

PmCHOTT,  G. — The  Adirondack  Spruce.  U.S.A. 
Eattray,  J.,  AND  Mill,  H.  E.— Forestry  and  Forestry  Products. 
Edinburgh,  1885. 

ScHLicn. — Forestry  Manual. 

Some  more  or  less  interesting  articles  on  ''Paper"  will 
be  found  in  the  following  encyclopaedias,  etc. : — 

DATE. 

1738.  Chambers's  Encycloi:)fedia. 

1757.  Barrow.    Dictionary  of  Arts. 

1759.  New,    Universal  History  of  Arts. 

1770.  Eoyal  Dictionary  of  Arts. 

1788.  Howard.    A  Eoyal  Encj^clopeedia. 

1806.  Gregory.    A  Dictionary  of  Arts  and  Sciences. 

1807.  Encyclopaedia  Perthen sis. 

1809.  Nicholson.    The  British  Encyclopaedia. 

1813.  Martin.    Circle  of  the  Mechanical  Arts. 

1813.  Pantologia. 

1819.  Eees'  Cyclopaedia. 

1821.  Encyclopaedia  Londoniensis. 

1827.  Jamieson's  Dictionary. 

1828.  Oxford  En cycloj^aedia. 

1829.  The  London  Encyclopaedia. 

1830.  Edinburgh  Encyclopaedia. 
1833.  Phillip's  Dictionary  of  Arts. 

1835.  Partington.    British  Cyclopaedia. 

1836.  Archaoologia,  vol.  xxvi. 

1836.  Barlow.    Encyclopaedia  of  Arts. 

1840.  The  Penny  Encyclopaedia. 

1845.  Encyclopaedia  Metropolitana. 

1848.  Useful  Arts  of  Great  Britain.  S.P.C.K. 

1851.  Knight's  Cyclopaedia  of  Industry. 

1855.  Apj)leton's  Dictionary  of  Mechanics. 

1860.  Hebert.    Mechanic's  Encyclopaedia. 

1861.  Knight's  English  Cyclopaedia. 
1861.  New  American  Cyclopaedia. 
1866.  Tomlinson's  Dictionary  of  Arts. 

1871.  Yeats.    The  Technical  History  of  Commerce. 

1874.  Clarke's  Practical  Magazine. 

1875.  Ure's  Dictionary  of  Arts. 


BTBLIOGEAPHY 


271 


1875.  Globe  Cyclopaedia. 

1876.  American  Mechanical  Dictionary. 

1877.  Johnson's  Universal  CyclopDedia. 
1880.  Wylde.    Industries  of  the  World. 
1882.  Spon's  Encyclopaedia  of  Manufactures. 
1886.  Encyclopaedia  Britannica. 

1889.  Chambers's  Encyclopaedia. 

1889.  Blaikie.    Modern  Cyclopaedia. 

1890.  Popular  Encyclopaedia. 
1892.  Spon's  Workshop  Eeceipts. 

1903.  Gilman.    International  Encyclopaedia. 

1904.  Encyclopaedia  Americana. 

1904.  Tweney's  Technological  Dictionary. 

Newspapers. 
England. 

Papermaker  and  British  Paper  Trade  Journal.  S.  C.  Phillips, 
London. 

Papermakers'  Circular.    Dean  &  Son,  London. 

Papermakers'  Monthly  Journal.    Marchant,  Sin^^er  &  Co.,  London. 
Paper  Box  and  Bag  Maker.    S.  C.  Phillips,  London. 
Papermaking.  London. 

The  Paper  and  Printing  Trades'  Journal.  London, 
World's  Paper  Trade  Eeview.    W.  J.  Stonhill,  London. 

Canada. 

Pulp  and  Paper  Magazine.    Biggar- Wilson,  Ltd.,  Toronto. 

United  States  of  America. 
American  Bookmaker.    Howard  Lockwood  &  Co.,  New  York. 
The  Paper  Trade.  Chicago. 

The  Stationer.    Ploward  Lockwood  &  Co.,  New  York. 
Paper  Mill  and  Wood  Pulp  News.    L.  D.  Post  &  Co.,  New  York. 
Paper  Trade  Journal.    Howard  Lockwood  &  Co.,  New  York. 
The  Paper  World.    C.  W.  Bryan  &  Co.,  Holyoke,  Mass. 

France. 

Bulletin  Journal  des  Eabricants  de  Papier.  Paris. 
Journal  des  Papetiers.    M.  Edmond  Eousset,  Paris. 
Le  Moniteur  de  la  Papeterie  Eran9aise.  Paris. 


272 


THE  MANUFACTUEE  OF  PAPEE 


La  Papeterie.  Paris. 

La  Eevue  de  la  Papeterie  Fraii9aise  et  Etrangere.  M.  Edmond 
Eousset,  Paris. 

Le  Papier.    H.  Everling,  Paris. 

Germany. 

Centralblatt  fur  die  Osterreichisch  "Ungarisclie  Papierindustrie. 
Adolf  Hladufka,  Wien. 

Der  Papierfabrikaut.    Otto  Eisner,  Berlin. 

Der  Papier  Markt.    Carl  Dobler,  Frankfurt  a.  Main. 

Deutsche  Papier  und  Schreibwarenzeitung.    S.  Eichter,  Berlin. 

Die  Postkarte.    Gustav  Fahrig,  Leipzig. 

Export-Journal.    G.  Hedeler,  Leipzig. 

Holzstoif-Zeitung,    Camillo  Dracbe,  Dresden. 

Papierliandler  Zeitung  fur  Osterreichungarn.  Wien. 

Papier-Industrie.  Berlin, 

Papier-und  Scbreibwaren-Zeitung.  Wien. 

Papier-Zeitung.    C.  Hofmann,  Berlin. 

Schweizer  Grapbischer  Central- Anzeiger.    H.  Keller,  Luzern. 
Wochenblatt    flir    Papierfabrikation.     Guntter-Staib  Biberach 
(Wurtt). 

Wocbenschrift  fur  den  Papier-und  Scbreibwarenbandel.  Dr.  H. 
Hirschberg,  Berlin. 


BIBLIOGEAPHY 


272a 


ANALYSIS,  TECHNOLOGY. 

Beadle  and  Stevens. — Blotting  paj)er,  nature  of  absorbency. 
1905. 

Winkler. — Estimation  of  Moisture  in  V/ ood-pulp.  1902.  Trans- 
lated by  Dr.  H.  P.  Stevens. 

Hauptversammlung. — Published  annually  by  the  Verein  der 
Zellstoff  und  Papier-Chemiker.    Berlin,  1907  et. 

FIBRES,  etc. 

Dodge,  C.  E. — Catalogue  of  useful  Fibre-j^lants  of  the  World. 
Eeport  No.  9.    Dept.  of  Agriculture.    L\6'.J.,  1897. 

Duchesne,  E.  A. — Eepertoire  des  plantes  utiles  et  des  plantes 
vuueneuses  du  globe,  etc.    Bruxelles,  1846. 

Gabalde,  B. — Essai  sur  le  bananier  et  ses  applications  a  la  fabrica- 
tion de  papier.  1843. 

Montessus  de  Ballore. — Alfa  et  papier  d'Alfa.  1908. 

Pecheux. — Les  textiles,  les  tissus,  le  papier.    6  pp.    Paris,  1907. 

Eenouard. — Etudes  sur  les  fibres  textiles.  Paris. 

Eenouard. — Les  fibres  textiles  do  I'Algerie.  Paris. 

Eiviere,  Auguste  et  Charles.  —  "  Les  Bambous."  Societe 
d'Acclimatation.  Paris. 

EiCHMOND,  G.  F. —  Philippine  Fibres  and  Fibrous  Substances. 
Manila,  Bureau  of  Printing,  1900. 

HISTORICAL. 

Briquet,  C.  M. — Eecherches  sur  les  premiers  Papiers  employes  du 
X«  au  XIV«  siecle.    pp.  77.    Paris,  1886. 

Briquet,  C.  M. — De  la  valeur  des  Filigraues  du  Papier  comme 
moyen  de  determiner  I'age  de  documents,    pp.13.    Geneve,  l'S^2. 

Briquet,  C.  M. — La  Legende  paleographique  du  Papier  de  Coton. 
pp.  18.    Geneve,  1884. 

Briquet,  C.  M. — Lettre  sur  les  Papiers  usites  en  Sicile  a  I'occasion 
de  deux  manuscrits  en  papier  dit  le  coton.    16  pp.    Palermo,  1892. 

Desmarest,  N. — Art  de  la  Papeterie.    Paris,  1879. 

Delon,  C. — Histoire  d'un  livre.    Paris,  1879. 


272b 


THE  MANUFACTUEE  OF  PAPER 


DiDOT,  A.  F. — Le  centenaire  de  la  Machine  a  Papier  continu. 
pp.  79.    Paris,  1900. 

Dickinson,  J.— Dickinson's  Paper  Mills.    Calcutta,  1884. 

GriRARD,  A. — Le  Papier  ses  ancetres  ;    son  histoire.    Lille,  1892. 

JuLiEN,  S. — Description  des  precedes  chinois  pour  la  fabrication 
du  papier.  Traduit  de  I'ouvrage  chinois  par  Thien-Kong-Kha-We. 
1840. 

Kay,  J. — Paper,  its  history,    pp.  100.    London,  1893. 
Lempertz,   H. — Beitrage  zur  Geschichte  des  Leinens  Papiers. 
Koln,  1891. 

PAPER  MANUFACTURE. 

BoEY,  P. — Les  Metamorphoses  d'un  Chiffon.    Abbeville,  1897. 
Chaerol,  L. — La  Eeglenientation  dii  Travail  dans  I'mdustrie  .  du 
papier,    pp.  168.    Paris,  1901. 

Demuth,  F. — Die  Papier  Fabrikation.  1903. 

Demuth,  F. — Die  Storungen  in  deutschen  Wirtschaftsleben  1900. 
Leipzifj,  1903. 

LiMOGE. — Cercles  d'li^tudes  commerciales,  Le  Papier,  pp.  140. 
Limo(je,  1892. 

PAPER,  SPECIAL  KINDS. 

Spalding  and  Hodge. — Printing  papers ;  a  handbook.  London, 
1905. 

STATISTICS,  etc. 

Beadle,  C. — Development  of  Water-marking.  London,  1906 
(Society  of  Arts). 

DuMERCY. — Bibliographie  de  la  PajDeterie.   pp.  28.    Bruxelles,  1888. 
Bruce,  H. — G-ladstone  and  Paper  Duties.    Edinbunjli,  1885. 
Ellis,  J.  B. — Hints  for  the  Paper  Warehouse.    L^eeds,  1887. 
Webster,  J. — Synopsis  of  Sizes  of  Paper.    Soutlq/ort,  1889. 
Whitson,  W. — The  Concise  Paper  Calculator.    Edinburgh,  1903. 

WOOD  PULP,  etc. 

Dropisch,  B. — Holzstoff  et  Holzcellulose.    Weimar,  1879. 


INDEX 


Acid  dyes,  201 

in  papers,  239 
size,  170 
Agave,  40 
Alum,  167,  168 
Aniline  dyes,  201 

sulphate,  121 
Animal  size,  63,  164 
AnticUors,  163 
Art  paper,  142 

imitation,  145 
testing,  147 
Asbestos,  174 
Ash  in  paper,  171 

Backwater,  120,  205 
Bagasse,  41 
Bamboo,  43 
Barker,  97 
Beating  engines,  186 
patents,  192 
power  consumed,  191 
Beating,  conditions  of,  197 

early  methods  of,  176 
experiments  in,  179 
process  of,  58,  175 
Bibliography,  253 
Bisulphite  of  lime,  159 
Bleaching,  57,  83 
powder,  161 
Blue  prints,  140 
Board  machine,  132,  135 
P. 


Boards,  manufacture  of,  131 

duplex,  132,  134 
Book  papers,  quality  of,  246 
Books,  decay  of,  237 
Brown  papers,  127 

Carbonic  acid  recorder,  215 
Casein,  165,  235 
Caustic  soda,  81,  155 
Cellulose,  21 

derivatives  of,  29 

hydrolysis  of,  27,  229 

oxidation  of,  28 

percentage  of,  in  plants,  23 

properties  of,  26 
Chemical  residues  in  paper,  238 

wood  pulp,  104 
Chemicals,  153 

China  clay,   117,  150,  171,  204, 
234 

Coal  consumption,  214 
Coated  paper,  142 
Cold  ground  pulp,  100 
Colophony,  169 

Colour  of  paper,  fading  of,  203, 
241 

matching,  205 
unevenness  of, 
203 

Colouring  of  paper  pulp,  199 

analysis  of,  206 
Cotton,  22,  69 

T 


274 


INDEX 


Cyanotype  papers,  140 
Cylinder  machine,  131 

Density  of  paper,  181 
Deterioration  of  paper,  228,  246 
Digesters,  52,  89,  109 
Dilution  tables,  157,  163 
Duplex  boards,  134 
Dyeing  of  paper,  199 

EiBEL  patent,  223 
Electrical  power,  219 
Electrolytic  bleaching,  57 
Engine  si^^ing,  117,  167 
Esparto,  72 

bleaching  of,  83 

composition  of,  73 

test  for,  in  papers,  87 

yield  of,  77 
Evaporation  apparatus,  76,  79 
tables,  81 

Eeatherweigiit  papers,  232 
Eibres  for  paper-making,  38 
examination  of,  43 
reagents  for  staining,  71 
Elax,  40 

Eourdrinier  machine,  early,  16 
Erencli  chalk,  173  ^ 

GrAS  producer,  218 
Gelatine,  63,  164,  237 
Glue,  137,  142,  235 
Grinders,  100 

History  of  paper,  1 
Hoernle,  7 

Hollander,  16,  59,  176,  185 
Hot  ground  pulp,  100 

Imitation  art  paper,  145,  235 
Kraft  paper,  129 
parchment,  137 


Improvements  in  paper-making, 
214 

Iron  in  paper,  229 
Kraft  papers,  128 

Laid  papers,  66 
Lime,  52,  157 

bisulphite,  159 

sulphate,  173 
Linen  fibre,  70 
Loading,  171 

M.  G.  caps,  130 
Machinery,  214,  224 
Manila  paper,  127 
Mechanical  pulp,  95 
detection  of,  121 
Metanil  yellow,  122 
Middles,  134 
Mitscherlich  pulp,  107 
Moisture,  influence  of,  243 
Multiple  effect  evaporation,  79 

Neutral  size,  169 
Newsi)aper,  116,  215 

Output  of  a  paper  machine,  122 

Paper,  art,  142 

ash  in,  171 
brown,  127 
bulk  of,  231 

chemical  residues  in,  238 
clay  in,  234 
colour  of,  199,  241 
colour  in,  analj'sis  of,  207 
deterioration  of,  229 
fibres  for,  38 
history  of,  1,5 
iron  in,  239 
permanence  of,  230 


INDEX 


275 


Paper,  rags  used  for,  47 
sizing  of,  G3 
special  kinds  of,  137 
standards  of  quality,  246 
strength  of,  184,  231 
surface  of,  233 
volume    composition  of, 
233 

Paper  machine,  early,  16 

output  of,  122 
Paj)ier-mache,  150 
Papyrus,  2,  42 
Paraffin  paper,  148 
Parchment,  4 

paper,  137 
Peat,  41 

Phloroglucine,  121 
Pigments,  199 
Porion  evajiorator,  76 
Presse-pate,  86 
Prussian  blue,  200 

Ea.g  paper,  manufacture  of,  47 

origin  of,  5 
Eags,  bleaching,  55 

boiling,  51 

classification,  48 

sorting,  48 
Ramie,  40 
Eecords,  early,  1 
Recovered  ash,  158 
Recovery  processes,  78,  113 
Refiners,  90 
Rope  browns,  127 
Rosin  size,  117,  169,  236 

Screens,  102 
Sealings,  129 
Shrinkage  of  paper,  181 
Sizing  of  paper,  63,  117,  167 
Society  of  Arts,  246 
Soda,  153 


Soda  pulp,  107,  113 

recovery,  78 

silicate  of,  166,  171 
Softening  of  water,  216 
Spent  liquors,  78,  113 
Staining  reagents  for  fibres,  71 
Standards  of  quality,  246,  248, 
250 

Starch,  166,  237 
Stationery  Ottice,  248 
Stone  beater  rolls,  189 
Straw,  88 
Sulphate  i:)u]p,  107 
Sulphite  im]}),  107 
Sulphites,  159,  163 
Supercalender,  65 
Superheated  steam,  218 

Tinfoil  paper,  148 
Transfer  paper,  149 

Ultramarine,  199 

Volume  composition  of  paper, 
233 

Vulcanised  fibre,  139 

Water  softening,  216 
Watermarks,  67 
Wavy  edges,  243 
Waxed  paper,  147 
Wet  press  machine,  103 
Wiesner,  6 
Willesden  2)aper,  139 
Wood,  22 
pulp,  95 

chemical,  104 

mechanical,  95 

soda,  107,  113 

sulphite,  107 
Wove  papers,  66 
Wra2:>pers,  127 


BHADBUKY.  AGNKW.  &  CO.  LD..  PRINTEKSJ,  LONDON  AND  TONBBIDGE. 


VAN  NOSTRAND'S 
"WESTMINSTER"  SERIES 

Bound  in  Uniform  Style. 
Fully  Illustrated.       Price  $2.00  net  each. 

Gas  Engines*  By  W.  J.  Marshall,  Assoc.  M.I.Mech.E., 
and  Capt.  H.  Riall  Sankey,  R.E.  (Ret.).  M.Inst.C.E., 
M.I.Mech.E.  300  Pages,  127  Illustrations. 
List  of  Contents  :  Theory  of  the  Gas  Engine.  The  Otto  Cycle.  The 
Two  Stroke  Cycle.  Water  Cooling  of  Gas  Engine  Parts.  Ignition. 
Operating  Gas  Engines.  The  Arrangement  of  a  Gas  Engine  Instal- 
lation. The  Testing  of  Gas  Engines.  Governing.  Gas  and  Gas 
Producers.  Index. 

Textiles*  By  A.  F.  Barker,  M.Sc,  with  Chapters  on  the 
Mercerized  and  Artificial  Fibres,  and  the  Dyeing  of 
Textile  Materials  by  W.  M.  Gardner,  M.Sc,  F.C.S.  ; 
Silk  Throwing  and  Spinning,  by  R.  Snow  ;  the  Cotton 
Industry,  by  W.  H.  Cook  ;  the  Linen  Industry,  by  F. 
Bradbury.    370  Pages.    86  Illustrations. 

Contents  :  The  History  of  the  Textile  Industries  ;  also  of  Textile 
Inventions  and  Inventors.  The  Wool,  Silk,  Cotton,  Flax,  etc., 
Growing  Industries.  The  Mercerized  and  Artificial  Fibres  em- 
ployed in  the  Textile  Industries.  The  Dyeing  of  Textile  Materials. 
The  Principles  of  Spinning.  Processes  preparatory  to  Spinning. 
The  Principles  of  Weaving.  The  Principles  of  Designing  and 
Colouring.  The  Principles  of  Finishing.  Textile  Calculations. 
The  Woollen  Industry.  The  Worsted  Industry.  The  Dress 
Goods,  Stuff,  and  Linings  Industry.  The  Tapestry  and  Carpet 
Industry.  Silk  Throwing  and  Spinning.  The  Cotton  Industry. 
The  Linen  Industry  historically  and  commercially  considered. 
Recent  Developments  and  the  Future  of  the  Textile  Industries. 
Index. 

Soils  and  Manures.  By  J.  Alan  Murray,  B.Sc.  367 
Pages.  33  Illustrations. 
Contents  :  Introductory.  The  Origin  of  Soils.  Ph3\sical  Proper- 
ties of  Soils.  Chemistry  of  Soils.  Biology  of  Soils.  Fertility. 
Principles  of  Manuring.  Phosphatic  Manures.  Phosphonitro- 
genous  Manures.  Nitrogenous  Manures.  Potash  Manures. 
Compound  and  Miscellaneous  Manures.  General  Manures.  Farm- 
yard Manure.  Valuation  of  Manures.  Composition  and  Manural 
Value  of  Various  Farm  Foods. 

(  I  ) 


THE  "WESTMINSTER''  SERIES 


Coal.    By  James  Tonge,  M.I.M.E.,  F.G.S.,  etc.  (Lecturer 
on  Mining  at  Victoria  University,  Manchester).  283 
Pages.  With  46  Illustrations,  many  of  them  showing  the 
Fossils  found  in  the  Coal  Measures. 
List  of  Contents  :    History.    Occurrence.    Mode  of  Formation 
of  Coal  Seams.    Fossils  of  the  Coal  Measures.    Botany  of  the 
Coal-Measure  Plants.    Coalfields  of  the  British  Isles.  Foreign 
Coalfields.    The  Classification  of  Coals.    The  Valuation  of  Coal. 
Foreign  Coals  and  their  Values.    Uses  of  Coal.    The  Production 
of  Heat  from  Coal.    Waste  of  Coal.    The  Preparation  of  Coal 
for  the  Market.    Coaling  Stations  of  the  World.  Index. 

Iron  and  SteeL   By  J.  H.  Stansbie,  B.Sc.  (Lond.),  F.I.C. 

385  Pages.  With  86  Illustrations. 
List  of  Contents  :  Introductory.  Iron  Ores.  Combustible  and 
other  materials  used  in  Iron  and  Steel  Manufacture.  Primitive 
Methods  of  Iron  and  Steel  Production.  Pig  Iron  and  its  Manu- 
facture. The  Refining  of  Pig  Iron  in  Small  Charges.  Crucible 
and  Weld  Steel.  The  Bessemer  Process.  The  Open  Hearth 
Process.  Mechanical  Treatment  of  Iron  and  Steel.  Physical 
and  Mechanical  Properties  of  Iron  and  Steel.  Iron  and  Steel 
under  the  Microscope.  Heat  Treatment  of  Iron  and  Steel.  Elec- 
tric Smelting.    Special  Steels.  Index. 

Timber*    By  J.  R.   Baterden,  Assoc.M.Inst.C.E.  334 

Pages.  54  Illustrations. 
Contents  :  Timber.  The  World's  Forest  Supply.  Quantities  of 
Timber  used.  Timber  imports  into  Great  Britain.  European 
Timber.  Timber  of  the  United  States  and  Canada.  Timbers 
of  South  America,  Central  America,  and  West  India  Islands.  Tim- 
bers of  Indig,,  Burma,  and  Andaman  Islands.  Timber  of  the 
Straits  Settlements,  Malay  Peninsula,  Japan  and  South  and 
West  Africa.  Australian  Timbers.  Timbers  of  New  Zealand 
and  Tasmania.  Causes  of  Decay  and  Destruction  of  Timber. 
Seasoning  and  Impregnation  of  Timber.  Defects  in  Timber  and 
General  Notes.  Strength  and  Testing  of  Timber.  "  Figure  "  in 
Timber.    Appendix.  Bibliography. 

Natural  Sources  of  Power.  By  Robert  S.  Ball,  B.Sc, 
A.M.Inst.C.E.  362  Pages.  With  104  Diagrams  and 
Illustrations. 

Contents  :  Preface.  Units  with  Metric  Equivalents  and  Abbre- 
viations. Length  and  Distance.  Surface  and  Area.  Volumes. 
Weights  or  Measures.  Pressures.  Linear  Velocities,  Angular 
Velocities.  Acceleration.  Energy.  Power.  Introductory 
Water  Power  and  Methods  of  Measuring.  Application  of  Water 
Power  to  the  Propulsion  of  Machinery.    The  Hydraulic  Turbine, 

(  2  ) 


THE  ''WESTMINSTER''  SERIES 


Various  Types  of  Turbine.  Construction  of  Water  Power  Plants. 
Water  Power  Installations.  The  Regulation  of  Turbines.  Wind 
•  Pressure,  Velocity,  and  Methods  of  Measuring.  The  Application 
of  Wind  Power  to  Industry.  The  Modern  Windmill.  Con- 
structional Details.  Power  of  Modern  Windmills.  Appendices. 
A,B,C  Index. 

Electric  Lamps,  By  Maurice  Solomon,  A.C.G.I., 
A.M.I. E.E.    339  Pages.    112  Illustrations. 

Contents  :  The  Principles  of  Artificial  Illumination.  The  Produc- 
tion of  Artificial  Illumination.  Photometry.  Methods  of  Testing. 
Carbon  Filament  Lamps.  The  Nernst  Lamp.  Metallic  Filament 
Lamps.  The  Electric  Arc.  The  Manufacture  and  Testing  of  Arc 
Lamp  Carbons.  Arc  Lamps.  Miscellaneous  Lamps.  Compari- 
son of  Lamps  of  Different  Types. 

Liquid  and  Gaseous  Fuels,  and  the  Part  they  play 
in  Modern  Power  Production.  By  Professor 
Vivian  B.  Lewes,  F.I.C,  F.C.S.,  Prof,  of  Chemistry, 
Royal  Naval  College,  Greenwich.  350  Pages.  With  54 
Illustrations. 

List  of  Contents  :  Lavoisier's  Discovery  of  the  Nature  of  Com- 
bustion, etc.  The  Cycle  of  Animal  and  Vegetable  Life.  Method 
of  determining  Calorific  Value.  The  Discovery  of  Petroleum 
in  America,  Oil  Lamps,  etc.  The  History  of  Coal  Gas.  Calorific 
Value  of  Coal  Gas  and  its  Constituents.  The  History  of  Water 
Gas.  Incomplete  Combustion.  Comparison  of  the  Thermal 
Values  of  our  Fuels,  etc.    Appendix.    Bibliography.  Index. 

Electric  Power  and  Traction.  By  F.  H.  Davies, 
A.M.!. E.E.    299  Pages.    With  66  Illustrations. 

List  of  Contents  :  Introduction.  The  Generation  and  Distri- 
bution of  Power.  The  Electric  Motor.  The  Application  of 
Electric  Power.  Electric  Power  in  Collieries.  Electric  Power 
in  Engineering  Workshops.  Electric  Power  in  Textile  Factories. 
Electric  Power  in  the  Printing  Trade.  Electric  Power  at  Sea. 
Electric  Power  on  Canals.  Electric  Traction.  The  Overhead 
System  and  Track  Work.  The  Conduit  System.  The  Surface 
Contact  System.  Car  Building  and  Equipment.  Electric  Rail- 
ways.   Glossary.  Index. 

Decorative  Glass  Processes.  By  Arthur  Louis 
DuTHiE.  279  Pages.  38  Illustrations. 
Contents  :  Introduction.  Various  Kinds  of  Glass  in  Use  :  Their 
Characteristics,  Comparative  Price,  etc.  Leaded  Lights.  Stained 
Glass.  Embossed  Glass.  Brilliant  Cutting  and  Bevelling.  Sand- 
Blast  and  Crystalline  Glass.  Gilding.  Silvering  and  Mosa/c. 
Proprietary  Processes.    Patents.  Glossary. 

(  3  ) 


THE  "WESTMINSTER"  SERIES 


Town  Gas  and  its  Uses  for  the  Production  of 
Light,  Heat,  and  Motive  Power*  By  W.  H.  Y. 
Webber,  C.E.    282  Pages.    With  71  Illustrations. 

List  of  Contents  :  The  Nature  and  Properties  of  Town  Gas.  The 
History  and  Manufacture  of  Town  Gas,  The  Bye-Products  of 
Coal  Gas  Manufacture.  Gas  Lights  and  Lighting.  Practical 
Gas  Lighting.  The  Cost  of  Gas  Lighting,  Heating  and  Warm- 
ing by  Gas,  Cooking  by  Gas,  The  Healthfulness  and  Safety 
of  Gas  in  all  its  uses.  Town  Gas  for  Power  Generation,  including 
Private  Electricity  Supply.  The  Legal  Relations  of  Gas  Sup- 
pliers, Consumers,  and  the  Public.  Index, 

Electro-Metallurgy*  By  J.  B.  C.  Kershaw,  F.I.C. 
318  Pages.  With  61  Illustrations. 
Contents  :  Introduction  and  Historical  Survey.  Aluminium. 
Production.  Details  of  Processes  and  Works.  Costs.  Utiliza- 
tion. Future  of  the  Metal.  Bullion  and  Gold.  Silver  Refining 
Process.  Gold  Refining  Processes.  Gold  Extraction  Processes. 
Calcium  Carbide  and  Acetylene  Gas.  The  Carbide  Furnace  and 
Process.  Production.  Utilization.  Carborundum.  Details  of 
Manufacture.  Properties  and  Uses.  Copper.  Copper  Refin- 
ing. Descriptions  of  Refineries.  Costs.  Properties  and  Utiliza- 
tion. The  Elmore  and  similar  Processes.  Electrolytic  Extrac- 
tion Processes.  Electro-Metallurgical  Concentration  Processes. 
Ferro-alloys.  Descriptions  of  Works.  Utilization.  Glass  and 
Quartz  Glass.  Graphite.  Details  of  Process.  Utilization.  Iron 
and  Steel.  Descriptions  of  Furnaces  and  Processes.  Yields  and 
Costs.  Comparative  Costs.  Lead.  The  Salom  Process.  The  Betts 
Refining  Process.  The  Betts  Reduction  Process,  White  Lead  Pro- 
cesses. Miscellaneous  Products.  Calcium.  Carbon  Bisulphide. 
Carbon  Tetra-Chloride.  Diamantine.  Magnesium.  Phosphorus. 
Silicon  and  ^its  Compounds.  Nickel.  Wet  Processes.  Dry 
Processes.  Sodium.  Descriptions  of  Cells  and  Processes.  Tin. 
Alkaline  Processes  for  Tin  Stripping.  Acid  Processes  for  Tin 
Stripping.  Salt  Processes  for  Tin  Stripping.  Zinc.  Wet  Pro- 
cesses. Dry  Processes.  Electro-Thermal  Processes.  Electro- 
Galvanizing.    Glossary.    Name  Index. 

Radio-Telegraphy*  By  C.  C.  F.  Monckton,  M.I.E.E. 
389  Pages.  With  173  Diagrams  and  Illustrations. 
Contents  :  Preface.  Electric  Phenomena.  Electric  Vibrations. 
Electro-Magnetic  Waves.  Modified  Hertz  Waves  used  in  Radio- 
Telegraphy.  Apparatus  used  for  Charging  the  Oscillator.  The 
Electric  Oscillator  :  Methods  of  Arrangement,  Practical  Details. 
The  Receiver  :  Methods  of  Arrangement,  The  Detecting  Ap- 
paratus, and  other  details.  Measurements  in  Radio-Telegraphy. 
The  Experimental  Station  at  Elmers  End  :  Lodge-Muirhead 
System.  Radio  -  Telegraph  Station  at  Nauen  :  Telefunken 
System.    Station  at  Lyngby  :    Poulsen  System.    The  Lodge- 

(  4  ) 


THE   -WESTMINSTER"  SERIES 


Mujrhead  System,  the  Marconi  System,  Telefunken  System,  and 
Poulsen  SyGtem.  Portable  Stations,  Radio-Telephony.  Ap- 
pendices :  The  Morse  Alphabet.  Electrical  Units  used  in  this 
Book.    International  Control  of  Radio-Telegraphy.  Index. 

India-Rubber  and  its  Manufacture,  with  Chapters 
on  Gutta-Percha  and  Balata.  By  H.  L.  Terry, 
F.I.C.,  Assoc.Inst.M.M.    303  Pages.    With  Illustrations. 

List  of  Contents  :  Preface.  Introduction  :  Historical  and 
General.  Raw  Rubber.  Botanical  Origin.  Tapping  the  Trees. 
Coagulation.  Principal  Raw  Rubbers  of  Commerce.  Pseudo- 
Rubbers.  Congo  Rubber.  General  Considerations.  Chemical 
and  Physical  Properties.  Vulcanization.  India-rubber  Planta- 
tions. India-rubber  Substitutes.  Reclaimed  Rubber.  Washing 
and  Drying  of  Raw  Rubber.  Compounding  of  Rubber.  Rubber 
Solvents  and  their  Recovery.  Rubber  Solution.  Fine  Cut  Sheet 
and  Articles  made  therefrom.  Elastic  Thread.  Mechanical 
Rubber  Goods.  Sundry  Rubber  Articles.  India-rubber  Proofed 
Textures.  Tyres.  India-rubber  Boots  and  Shoes.  Rubber  for 
Insulated  Wires.  Vulcanite  Contracts  for  India-rubber  Goods. 
The  Testing  of  Rubber  Goods.  Gutta-Percha.  Balata.  Biblio- 
graphy. Index. 

The  Railway  Locomotive*  What  It  Is,  and  Why  It  is 

What  It  Is.  By  Vaughan  Pendred,  M.Inst.M.E., 
Mem. Inst. M.I.    321  Pages.    94  Illustrations. 

Contents  :  The  Locomotive  Engine  as  a  Vehicle — Frames.  Bogies. 
The  Action  of  the  Bogie.  Centre  of  Gravity.  Wheels.  Wheel 
and  Rail.  Adhesion.  Propulsion.  Counter-Balancing.  The  Loco- 
motive as  a  Steam  Generator — The  Boiler.  The  Construction  of  the 
Boiler.  Stay  Bolts.  The  Fire-Box.  The  Design  of  Boilers. 
Combustion.  Fuel.  The  Front  End.  The  Blast  Pipe.  Steam 
Water.  Priming.  The  Quality  of  Steam.  Superheating.  Boiler 
Fittings.  The  Injector,  The  Locomotive  as  a  Steam  Engine — 
Cylinders  and  Valves.  Friction.  Valve  Gear.  Expansion.  The 
Stephenson  Link  Motion.  Walschaert's  and  Joy's  Gears.  Slide 
Valves.  Compounding.  Piston  Valves.  The  Indicator.  Ten- 
ders. Tank  Engines.  Lubrication.  Brakes.  The  Running  Shed. 
The  Work  of  the  Locomotive. 

Glass  Manufacture.  By  Walter  Rosenhain,  Superin- 
tendent of  the  Department  of  Metallurgy  in  the  National 
Physical  Laboratory,  late  Scientific  Adviser  in  the  Glass 
Works  of  Messrs.  Chance  Bros.  &  Co.  280  Pages.  With 
Illustrations. 

Contents:  Preface.    Definitions.    Physical  and  Chemical  Qualities, 
Mechanical,  Thermal,  and  Electrical  Properties.  Transparency 

( 5  ) 


THE  "WESTMINSTER"  SERIES 


and  Colour.  Raw  materials  of  manufacture.  Crucibles  and 
Furnaces  for  Fusion,  Process  of  Fusion.  Processes  used  in 
Working  of  Glass.  Bottle.  Blown  and  Pressed.  Rolled  or 
Plate.  Sheet  and  Crown.  Coloured.  Optical  Glass  :  Nature 
and  Properties,  Manufacture.  Miscellaneous  Products.  Ap- 
pendix.   Bibliography  of  Glass  Manufacture.  Index 

Precious  Stones*   By  W.  Goodchild,  M.B.,  B.Ch.  319 
Pages.    With  42  Illustrations.    With  a  Chapter  on 
Artificial  Stones.    By  Robert  Dykes. 

List  of  Contents  :  Introductory  and  Historical.  Genesis  of 
Precious  Stones.  Physical  Properties.  The  Cutting  and  Polish- 
ing of  Gems.  Imitation  Gems  and  the  Artificial  Production  of 
Precious  Stones.  The  Diamond.  Fluor  Spar  and  the  Forms  of 
Silica,  Corundum,  including  Ruby  and  Sapphire.  Spinel  and 
Chrysoberyl.  The  Carbonates  and  the  Felspars.  The  Pyroxene 
and  Amphibole  Groups.  Beryl,  Cordierite,  Lapis  Lazuli  and  the 
Garnets.  Olivine,  Topaz,  Tourmaline  and  other  Silicates.  Phos- 
phates, Sulphates,  and  Carbon  Compounds. 

INTRODUCTION  TO  THE 

Chemistry  and  Physics  of  Building  Materials^ 

By  Alan  E.  Munby,  M.A.    365  Pages.  Illustrated. 

Contents  :  Elementary  Science  :  Natural  Laws  and  Scientific  In- 
vestigations. Measurement  and  the  Properties  of  Matter.  Air 
and  Combustion.  Nature  and  Measurement  of  Heat  and  Its 
Effects  on  Materials.  Chemical  Signs  and  Calculations.  Water 
and  Its  Impurities.  Sulphur  and  the  Nature  of  Acids  and  Bases. 
Coal  and  Its  Products.  Outlines  of  Geology.  Building  Materials  : 
The  Constituefits  of  Stones,  Clays  and  Cementing  Materials.  Clas- 
sification, Examination  and  Testing  of  Stones,  Brick  and  Other 
Clays.  Kiln  Reactions  and  the  Properties  of  Burnt  Clays.  Plasters 
and  Limes.  Cements.  Theories  upon  the  Setting  of  Plasters  and 
Hydraulic  Materials.  Artificial  Stone.  Oxychloride  Cement. 
Asphalte.  General  Properties  of  Metals.  Iron  and  Steel.  Other 
Metals  and  Alloys.  Timber.  Paints:  Oils,  Thinners  and  Varnishes ; 
Bases,  Pigments  and  Driers. 

Patents,  Designs  and  Trade  Marks  :  The  Law 
and  Commercial  Usage*  By  Kenneth  R.  Swan, 
B.A.  (Oxon.),  of  the  Inner  Temple,  Barrister-at-Law. 
402  Pages. 

Contents  :  Table  of  Cases  Cited — Part  I. — Letters  Patent.  Intro- 
duction. General.    Historical.   I.,   II.,   III.  Invention,  Novelty, 

(  6  ) 


THE  "WESTMINSTER"  SERIES 


Subject  Matter,  and  Utility  the  Essentials  of  Patentable  Invention. 
IV.  Specification.  V.  Construction  of  Specification.  VI.  Who 
May  Apply  for  a  Patent.  VII.  Application  and  Grant.  VIII. 
Opposition.  IX.  Patent  Rights.  Legal  Value,  Commercial 
Value.  X.  Amendment.  XI.  Infringement  of  Patent.  XII. 
Action  for  Infringement.  XIII.  Action  to  Restrain  Threats. 
XIV.  Negotiation  of  Patents  by  Sale  and  Licence.  XV.  Limita- 
tions on  Patent  Right.  XVI.  Revocation.  XVII.  Prolonga- 
tion. XVIII.  Miscellaneous.  XIX.  Foreign  Patents.  XX. 
Foreign  Patent  Laws  :  United  States  of  America.  Germany. 
France.    Table  of  Cost,  etc.,  of  Foreign  Patents.    Appendix  A. — 

I.  Table  of  Forms  and  Fees.  2.  Cost  of  Obtaining  a  British 
Patent.  3.  Convention  Countries.  Part  II. — Copyright  in 
Design.  Introduction.  I.  Registrable  Designs.  II.  Registra- 
tion. III.  Marking.  IV.  Infringement.  Appendix  B. — i. 
Table  of  Forms  and  Fees.  2.  Classification  of  Goods.  Part 
III. — Trade  Marks.    Introduction.    I.  Meaning  of  Trade  Mark. 

II.  Qualification  for  Registration.  III.  Restrictions  on  Regis- 
tration. IV.  Registration.  V.  Effect  of  Registration.  VI. 
Miscellaneous.  Appendix  C. — Table  of  Forms  and  Fees.  Indices. 
I.  Patents.    2.  Designs.    3.  Trade  Marks. 


The  Book:  Its  History  and  Development,  By 

Cyril  Davenport,  V.D.,  F.S.A.  266  Pages.  With 
7  Plates  and  126  Figures  in  the  text. 

List  of  Contents  :  Early  Records.  Rolls,  Books  and  Book 
bindings.  Paper.  Printing.  Illustrations.  Miscellanea. 
Leathers.  The  Ornamentation  of  Leather  Bookbindings  without 
Gold.  The  Ornamentation  of  Leather  Bookbindings  with  Gold. 
Bibliography.  Index. 


The  Manufacture  of  Paper.  By  R.  W.  Sindall,  F.C.S., 
Consulting  Chemist  to  the  \\'ood  Pulp  and  Paper  Trades  ; 
Lecturer  on  Paper-making  for  the  Hertfordshire  County 
Council,  the  Bucks  County  Council,  the  Printing  and 
Stationery  Trades  at  Exeter  Hall  (1903-4),  the  Institute 
of  Printers  ;  Technical  Adviser  to  the  Government  of 
India,  1905.    275  Pages.    58  Illustrations. 

Contents  :  Preface.  List  of  Illustrations.  Historical  Notice.  Cel- 
lulose and  Paper-making  Fibres.  The  Manufacture  of  Paper  from 
Rags,  Esparto  and  Straw.  Wood  Pulp  and  Wood  Pulp  Papers. 
Brown  Papers  and  Boards.  Special  kinds  of  Paper.  Chemicals 
used  in  Paper-making.  The  Process  of  "  Beating."  The  Dye- 
ing and  Colouring  of  Paper  Pulp.  Paper  Mill  Machinery.  The 
Deterioration  of  Paper.    Bibliography.  Index. 

(  7  ) 


THE  ^'WESTMINSTER"  SERIES 


Wood  Pulp  and  its  Applications.  By  C.  F.  Cross, 
B.Sc,  F.I.C.,  E.  J.  Bevan,  F.I.C,  and  R.  W.  Sindall, 
F.C.S.    266  pages.    36  Illustrations. 

Contents  :  The  Structural  Elements  of  Wood.  Cellulose  as  a 
Chemical.  Sources  of  Supply.  Mechanical  Wood  Pulp.  Chemical 
Wood  Pulp.  The  Bleaching  of  Wood  Pulp.  News  and  Printings. 
Wood  Pulp  Boards.  Utilisation  of  Wood  Waste.  Testing  of 
Wood  Pulp  for  Moisture.  Wood  Pulp  and  the  Textile  Industries. 
Bibliography.  Index. 


Photography:   its   Principles  and  Applications* 

By  Alfred  Watkins,  F.R.P.S.  342  pages.  98  Illus- 
trations. 

Contents  :  First  Principles.  Lenses.  Exposure  Influences.  Prac- 
tical Exposure.  Development  Influences.  Practical  Develop- 
ment. Cameras  and  Dark  Room.  Ortho chromatic  Photography, 
Printing  Processes.  Hand  Camera  Work.  Enlarging  and  Slide 
Making.  Colour  Photography.  General  Applications.  Record 
Applications,  Science  Applications.  Plate  Speed  Testing.  Pro- 
cess Work.   ^Addenda.  Index. 


IN  PREPARATION- 

Commercial  Paints  and  Painting*  By  A.  S.  Jenn- 
ings, Hon.  Consulting  Examiner,  City  and  Guilds  of 
London  Institute. 

Brewing  and  Distilling*   By  James  Grant,  F.S.C. 


(  8  ) 


Date  Due 

1 

■  ^ 

FEB  2 

 . 

